Integrated circuit testing

ABSTRACT

Systems and methods of testing integrated circuits are disclosed. A system may include a data compression component to compress data received from an integrated circuit under test at a first clock frequency, to generate compressed data. The system may also include a data output component, operatively coupled to the data compression component, to convey the compressed data to automated testing equipment at a second clock frequency.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.13/609,019, filed Sep. 10, 2012, which is a continuation of U.S.application Ser. No. 13/162,112, filed Jun. 16, 2011, now U.S. PatentNo. 8,286,046, which is a continuation of U.S. application Ser. No.11/552,938, entitled “Integrated Circuit Testing Module Including SignalShaping Interface,” and filed Oct. 25, 2006, now U.S. Pat. No.8,001,439, which is in turn a continuation-in-part of U.S. applicationSer. No. 11/369,878 entitled “Integrated Circuit Testing ModuleIncluding Data Compression,” and filed Mar. 6, 2006, now U.S. Pat. No.7,370,256 which is in turn: a continuation-in-part of U.S. applicationSer. No. 11/304,445 entitled “Integrated Circuit Testing Module” filedon Dec. 14, 2005, now U.S. Pat. No. 7,265,570; a continuation-in-part ofco-pending U.S. application Ser. No. 10/824,734 entitled “Chip TestingWithin a Multi-Chip Semiconductor Package,” filed on Apr. 15, 2004, nowU.S. Pat. No. 7,139,945; a continuation-in-part of U.S. application Ser.No. 10/870,365 entitled “Testing of Integrated Circuit Devices,” filedon Jun. 17, 2004, now U.S. Pat. No. 7,103,815 which is a continuation ofapplication Ser. No. 09/967,389, filed on Sep. 28, 2001, now U.S. Pat.No. 6,754,866; a continuation-in-part of U.S. application Ser. No.11/083,473 entitled “Internally Generating Patterns For Testing In AnIntegrated Circuit Device,” filed on Mar. 18, 2005, now U.S. Pat. No.7,313,740, which is a continuation in part of U.S. patent applicationSer. No. 10/205,883 entitled “Internally Generating Patterns For TestingIn An Integrated Circuit Device,” filed on Jul. 25, 2002, which isabandoned; a continuation-in-part of U.S. application Ser. No.11/108,385 entitled “Bonding Pads for Testing of a SemiconductorDevice,” filed on Apr. 18, 2005, now U.S. Pat. No. 7,259,582, which is adivision of application Ser. No. 10/608,613, filed on Jun. 27, 2003, nowU.S. Pat. No. 6,882,171, which is a continuation-in-part of applicationSer. No. 10/305,635, filed on Nov. 27, 2002, now U.S. Pat. No.6,812,726; a continuation-in-part of U.S. application Ser. No.11/207,518 entitled “Architecture and Method for Testing of anIntegrated Circuit Device,” and filed on Aug. 19, 2005, now U.S. Pat.No. 7,444,575; a continuation-in-part of U.S. application Ser. No.11/223,286 entitled “Shared Bond Pad for Testing a Memory within aPackaged Semiconductor Device,” and filed Sep. 9, 2005, now U.S. Pat.No. 7,245,141 which is a continuation-in-part of U.S. patent applicationSer. No. 11/108,385, filed on Apr. 18, 2005, now U.S. Pat. No. 7,259,582which is a divisional of U.S. Pat. No. 6,882,171 filed on Jun. 27, 2003,which is a continuation-in-part of U.S. Pat. No. 6,812,726, filed onNov. 27, 2002, U.S. application Ser. No. 11/223,286 is also acontinuation-in-part of U.S. patent application Ser. No. 10/679,673,filed on Oct. 3, 2003, now U.S. Pat. No. 7,006,940; and acontinuation-in-part of U.S. application Ser. No. 11/258,484 entitled“Component Testing and Recovery,” and filed Oct. 24, 2005, now U.S. Pat.No. 7,404,117. The present application hereby claims priority under 35U.S.C. §120 to the above-listed U.S. patent applications. Moreover, theentireties of the above-listed U.S. patents and patent applications arehereby incorporated by reference herein.

BACKGROUND

1. Field of the Invention

The current invention relates to integrated circuit devices, and inparticular, to the testing of integrated circuit devices.

2. Related Art

An integrated circuit (IC) device may comprise many miniaturizedcircuits implemented in a semiconductor substrate. IC devices must betested in order to ensure proper operation before they are used. ICdevices can be tested in a limited fashion using built-in self test(BIST) circuitry that is implemented within the IC devices themselves.BIST testing, however, is incomplete and does not test all aspects ofthe device's operation. Thorough testing of an IC device is accomplishedwith complex and expensive external testing equipment.

As the complexity and clock speeds of ICs increase, the capabilities ofexisting external testing equipment can become a limiting factor in thetesting of new ICs. For example, the clock speeds of the fastest memorydevices increase on almost an annual basis. These memory devices cannotbe tested at their maximum clock speeds using older testing equipmentthat was built for testing slower memory. In addition, the length of thecables between existing external testing equipment and the ICs undertest (on the order of one to five meters) results in input signals tothe IC device having slew rates too slow to reliably test parameterssuch as minimum set-up and hold times. Because of their cost, it isimpractical to purchase new testing equipment with each advance in clockspeeds. There is, therefore, a need for improved systems and methods oftesting integrated circuits.

SUMMARY

The present invention includes, in various embodiments, a test moduleconfigured to operate between testing equipment and one or moreintegrated circuits to be tested. The test module is configured tocommunicate with the testing equipment at a first slew rate and tocommunicate with the integrated circuits to be tested at a second,typically faster, slew rate. In some embodiments, the test moduleincludes components configured to generate addresses, commands, and testdata for testing of memory devices responsive to data and commandsreceived from the testing equipment. These memory devices can include,for example, DRAM (Dynamic Random Access Memory), SRAM (Static RandomAccess Memory), Flash Memory, or the like.

The integrated circuits to be tested are optionally embedded within anelectronic device. For example, in some embodiments, the integratedcircuits to be tested are memory circuits within a system-on-chip (SoC),system-in-package (SiP), system-in-module (SiM), module-in-module (MiM),package-over-package (POP), package-in-package (PiP), or the like. Inthese embodiments, the test module can be configured to operate theelectronic device in a first mode wherein shared inputs to theelectronic device are used to test first circuits within the electronicdevice, and a second mode wherein the shared inputs are used tocommunicate with other circuits within the electronic device. Thus, insome embodiments, the test module is configured to test circuits at aclock frequency faster than testing equipment being used, while alsocommunicating to the circuits being tested in a test mode through sharedinputs.

In some embodiments, the test module is configured to include a testplan memory component configured to store one or more test plans. A testplan may include a sequence of test patterns and/or conditional brancheswhereby the tests to be performed next are dependent on the results ofthe preceding tests. The test plan memory may, optionally, be detachablefrom the test module.

In various embodiments, the test system, as a whole, is capable ofmultiple layers of programming. For example, at one level, standard ormore generic tests used for testing multiple classes of integratedcircuit devices may be programmed and stored in non-detachablecomponents of the test module. Other, device-specific tests may beprogrammed prior to each test session and downloaded into test planmemory. In addition, tests frequently updated may be more suited tobeing programmed and downloaded into one or more components of the testmodule prior to each test session or communicated to the test moduleduring a test session. Through various combinations of how and where tostore and/or input different portions of test plans, the invention isflexible and capable of multiple layers of programming.

In some embodiments, the test module includes a clock adjustmentcomponent configured to test time and slew sensitive parameters such asset-up time and hold time. The clock adjustment component is configuredto receive an input clock signal from, for example, the automatedtesting equipment, and make an adjustment to one or more of its outputsignals. In some embodiments, an adjustment is made to the clock signalsent from the test module, resulting in a uniform adjustment to testsignals sent to the integrated circuit. This uniform adjustment enablestesting of parameters such as set-up time and hold-time of theintegrated circuit as a whole.

In other embodiments, the adjustment is made to individual data channelsof the test signals sent from the test module to the integrated circuit.By adjusting, for example, one or more bits of a test data pattern orone or more address lines sent to the integrated circuit, the testmodule is capable of testing the sensitivity of the integrated circuitto a variety of time critical and slew rate sensitive parameters, suchas set-up and hold time.

Various embodiments of the invention include a system comprising one ormore input components configured to receive signals having a first slewrate from an automated testing equipment configured to test anintegrated circuit, one or more data generating components configured togenerate test signals responsive to the signals received from theautomated testing equipment, and one or more output componentsconfigured to convey the generated test signals to the integratedcircuit at a second slew rate, the integrated circuit being detachablefrom the one or more output components, the second slew rate beingfaster than the first slew rate.

Various embodiments of the invention include a method comprisingattaching an automated testing equipment to a test module having a clocksynchronization component, attaching an integrated circuit to be testedto the test module, receiving signals having a first slew rate from theautomated testing equipment at the test module, generating test signalswithin the test module responsive to the signals received from theautomated testing equipment, and sending the generated test signals tothe integrated circuit at a second slew rate faster than the first slewrate.

Various embodiments of the invention include a system comprising meansfor connecting a test module having a clock synchronization componentbetween an automated testing equipment and an integrated circuit to betested, means for receiving signals having a first slew rate from theautomated testing equipment at the test module, means for generatingtest signals within the test module responsive to the signals receivedfrom the automated testing equipment, and means for sending thegenerated test signals to the integrated circuit at a second slew ratefaster than the first slew rate.

Various embodiments of the invention include a system comprising a clocksynchronization component, one or more input components configured toreceive signals from an automated testing equipment configured to testan integrated circuit, one or more data generating components configuredto generate test signals responsive to the signals received from theautomated testing equipment, a clock adjustment component configured toadjust synchronization between the clock synchronization component andone or more elements of the generated test signals to be conveyed fromthe one or more output components to the integrated circuit in responseto the signals received from the automated testing equipment, and one ormore output components configured to convey the generated test signalsto the integrated circuit, the integrated circuit being separable fromthe one or more output components.

Various embodiments of the invention include a method comprisingattaching an automated testing equipment to a test module having a clockadjustment component, attaching an integrated circuit to be tested tothe test module, receiving signals from the automated testing equipmentat the test module, testing the integrated circuit according to thesteps of: generating an adjustment to the clock synchronizationresponsive to the signals received from the automated testing equipment,generating test signals within the test module responsive to the signalsreceived from the automated testing equipment, conveying the generatedtest signals to the integrated circuit using the adjustment to the clocksynchronization, receiving data from the integrated circuit responsiveto the conveyed generated test signals, and comparing the received datato an expected result

Various embodiments of the invention include a system comprising meansfor connecting a test module between an automated testing equipment andan integrated circuit to be tested, means for configuring the testmodule for testing of the integrated circuit, means for receivingsignals from the automated testing equipment at the test module, meansfor testing the integrated circuit according to the steps of: means forgenerating an adjustment to the clock synchronization responsive to thesignals received from the automated testing equipment, means forgenerating test signals within the test module responsive to the signalsreceived from the automated testing equipment, means for conveying thegenerated test signals to the integrated circuit using the adjustment tothe clock synchronization, means for receiving data from the integratedcircuit responsive to the conveyed generated test signals, and means forcomparing the received data to an expected result.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention and forfurther features and advantages, reference is made to the followingdescription taken in conjunction with accompanying drawings, in which:

FIG. 1 is a block diagram of a test system, according to variousembodiments of the invention;

FIG. 2 is a block diagram of a test module, according to variousembodiments of the invention;

FIGS. 3A and 3B illustrate test mode commands, according to oneembodiment of the invention;

FIG. 4 illustrates further details of an address generator, according tovarious embodiments of the invention;

FIG. 5 illustrates further details of data paths used for writing datato, and reading data from, an integrated circuit, according to variousembodiments of the invention;

FIG. 6 is a block diagram illustrating further details of a data writeregister, according to various embodiments of the invention;

FIGS. 7A and 7B include tables illustrating several examples of dataexpansion using the systems illustrated by FIG. 6, according to variousembodiments of the invention;

FIGS. 8A-8H illustrate a variety of test data patterns as may bedelivered to an integrated circuit from a test module, according tovarious embodiments of the invention;

FIG. 9 illustrates an embodiment of a command driver configured toschedule delivery of commands to an integrated circuit, according tovarious embodiments of the invention;

FIG. 10 includes a table illustrating clock cycle-based commandscheduling, according to various embodiments of the invention;

FIG. 11 illustrates a test mounting board including at least one testmodule and at least one mount configured to receive an integratedcircuit, according to various embodiments of the invention;

FIG. 12 illustrates a test array including a plurality of test mountingboards, according to various embodiments of the invention;

FIG. 13 illustrates methods of testing an integrated circuit using atest module, according to various embodiments of the invention;

FIG. 14 illustrates methods of generating test data, according tovarious embodiments of the invention;

FIG. 15 illustrates methods of processing test results received from anintegrated circuit, according to various embodiments of the invention;

FIG. 16 illustrates alternative methods of processing test resultsreceived from an integrated circuit, according to various embodiments ofthe invention;

FIG. 17 illustrates methods of generating address data, according tovarious embodiments of the invention;

FIG. 18 illustrates methods of command scheduling, according to variousembodiments of the invention;

FIG. 19 illustrates methods of configuring a test array for testing aplurality of integrated circuits, according to various embodiments ofthe invention;

FIG. 20 illustrates embodiments of the invention wherein a test moduleis configured to test a plurality of integrated circuits;

FIG. 21 illustrates logic used in serial compression following readingof data from an integrated circuit being tested;

FIGS. 22A and 22B illustrate the application of the serial compressionlogic of FIG. 21;

FIG. 23 illustrates logic used in parallel compression following theserial compression of FIG. 21;

FIG. 24 illustrates a method of compressing data according to variousembodiments of the invention;

FIG. 25 is a block diagram of an alternative embodiment of a testmodule, including a clock adjustment circuit and a test plan memory,according to various embodiments of the invention;

FIG. 26 illustrates a slew rate of a test signal;

FIGS. 27A-27D illustrate the relationship between a clock referencesignal conveyed from a Clock Driver to an IC, the generated testsignals, and the clock reference controlling the generated test signals,according to various embodiments of the invention;

FIG. 28 illustrates methods of testing the set-up time or hold time ofan integrated circuit, according to various embodiments of the invention

FIG. 29 illustrates a circuit diagram for testing the set-up time orhold time of an integrated circuit, according to various embodiments ofthe invention; and

FIG. 30 illustrates methods of testing an integrated circuit using atest module including a clock adjustment, according to variousembodiments of the invention.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the invention include a test module configured tooperate between automated testing equipment and one or more integratedcircuits to be tested. The test module is configured to receive data,addresses and instructions from the automated testing equipment and touse these data and instructions to generate additional data andaddresses. The test module is further configured to use the generateddata and addresses to test the integrated circuit, to receive testresults from the integrated circuit, and to report these test results tothe automated testing equipment.

Communication between the automated testing equipment and the testmodule is optionally at a different clock frequency than communicationbetween the test module and the integrated circuit being tested. Assuch, through the use of the test module, automated testing equipmentconfigured to operate at a first frequency can be used to test anintegrated circuit at a second higher frequency. For example, automatedtest equipment configured to test memory devices at 150 MHz may be usedto test memory devices at 300 MHz or more.

The test module is configured to be placed in close proximity to or onthe same silicon die as the integrated circuit to be tested. In part,because of the close proximity, the slew rate of the output signals tothe integrated circuit can be faster than the slew rate of the inputsignals from the automated testing equipment to the test module. Variousembodiments of the invention are, therefore, capable of delivering moreprecisely shaped test signals to the circuit to be tested, relative tothe automated testing equipment. Further benefits of the fast slew rateinclude, for example, a lower probability of false test results, a lowerprobability of noise interference, and an increased overall reliabilityof the tests.

In order to test a memory at a frequency greater than communications arereceived from the automated testing equipment, the test module includescomponents configured to automatically generate memory addresses andtest data responsive to an address and test data received from theautomated testing equipment. As is described further herein, thesecomponents are optionally programmable to generate a variety of testpatterns.

The test module further includes components configured to receive datafrom an integrated circuit being tested and either report a summary ofthese received data to the automated testing equipment, or compare thereceived data to expected data and report the results of this comparisonto the automated testing equipment. Thus, the test module is configuredto receive test results at a first frequency and communicate to theautomated testing equipment in response to these results at a second,optionally lower, frequency.

In some embodiments, the test module further includes a commandscheduler configured to communicate commands from the test module to theintegrated circuit being tested at intervals appropriate for testing theintegrated circuit. For example, if thorough testing of an integratedcircuit requires that the integrated circuit receive two commands withinthree clock cycles, the command scheduler may be programmed to conveythese commands with this interval, even though these commands may bereceived by the test module from the automated testing equipment at adifferent interval.

In some embodiments, the test module further includes a clock adjustmentcomponent configured to test aspects of an integrated circuit related toclock synchronization, for example set-up time and hold time. Anadjustment may be made to the clock signal sent to the integratedcircuit, for example in response to a signal received from the automatedtesting equipment. The adjustment optionally affects test signals sentto the integrated circuit uniformly, thereby enabling testing ofparameters such as set-up time and hold-time of the integrated circuitas a whole.

In another embodiment, an adjustment may be made to the clock signal toindividually control the output of individual data channels of thecommands, addresses, and/or data patterns sent to the integratedcircuit. Through individual adjustments of, for example, one bit or oneaddress line alone, the test module is capable of testing thesensitivity of the integrated circuit to a variety of time critical andslew rate sensitive parameters, such as set-up and hold time.

For the purposes of illustration, the testing of memory devices isdiscussed herein. However, the scope of the invention and the examplesprovided are intended to extend to other types of integrated circuitsincluding logic devices, processors, analog circuits, applicationspecific integrated circuits (ASICs), communication circuits, opticalcircuits, or the like. Further, the scope of the invention is intendedto apply to the testing of circuit assemblies such as system-on-chip(SoC), system-in-package (SiP), system-in-module (SiM), module-in-module(MiM), package-over-package (POP), package-in-package (PiP), or thelike. Examples referring to one of these assemblies are intended to beapplicable to others.

FIG. 1 is a block diagram of a Test System, generally designated 100,according to various embodiments of the invention. Test System 100includes an automated test equipment (ATE) 110 configured for testingintegrated circuits at a first frequency, and a Test Module 120configured to serve as an interface between ATE 110 and an integratedcircuit (IC) 130 to be tested. In some embodiments, Test Module 120 andIC 130 are included in the same electronic device. For example, TestModule 120 and IC 130 may both be within the same SiP. In someembodiments, Test Module 120 and IC 130 are included in the same silicondie. In some embodiments, Test Module 120 is a separate device from IC130.

Test System 100 optionally further includes a Clock 140 configured toprovide a clock reference signal to Test Module 120. ATE 110 isconfigured to communicate with Test Module 120 through an N-ChannelInterface 115 at the first frequency, and Test Module 120 is configuredto communicate with IC 130 through an M-Channel Interface 125. In someembodiments, the number of channels in N-Channel Interface 115 is thesame as the number of channels in M-Channel Interface 125. In someembodiments, the number of channels in M-Channel Interface 125 is amultiple of the number of channels in N-Channel Interface. N-ChannelInterface 115 and M-Channel Interface 125 can include, for example, atest pad, test probe, cable, test pin, or other connector. In someembodiments, M-Channel Interface 125 includes internal connectionswithin a system-on-chip (SoC), system-in-package (SiP), system-in-module(SiM), module-in-module (MiM), package-over-package (POP),package-in-package (PiP), or the like. Test Module 120 is optionallyphysically detachable from IC 130 and from ATE 110.

ATE 110 is optionally a prior art automated testing equipment configuredto test integrated circuits. For example, ATE 110 may include testequipment currently offered by Advantest Corporation of Tokyo, Japan,Teradyne, Inc. of Boston, Massachusetts, or Agilent Technologies, Inc.of Palo Alto, California. ATE 110 is characterized by a maximumfrequency at which it is configured to communicate with an integratedcircuit during testing.

Typically, ATE 110 is programmable to perform specific testing routinesas directed by a user. These testing routines include sending (i.e.,writing) test data, commands and optionally addresses via N-ChannelInterface 115. These test data, commands and addresses are received byTest Module 120. ATE 110 is further configured to receive (i.e., read)test results via N-Channel Interface 115, to compare the receivedresults with expected results, and to report variations between thereceived and expected results.

In alternative embodiments, ATE 110 is configured to include Test Module120 as a module. For example, in some embodiments, Test Module 120 isincluded in ATE 110 as a replaceable component that can be exchangedand/or upgraded as the technical requirements (e.g., testing frequency,form factor, command vocabulary, or the like) for testing evolve. Thus,in one embodiment, ATE 110 is configured to be upgraded by exchanginginstances of Test Module 120.

Test Module 120 is configured to receive test data, commands, andoptionally addresses from ATE 110 via N-Channel Interface 115 and to usethis received information to generate additional test data andoptionally additional addresses for testing of IC 130. For example, insome embodiments, Test Module 120 is configured to receive memorycontrol commands, data for testing memory, and memory addresses from ATE110. The received memory control commands, data and memory addresses areused to generate further data and further memory addresses for testingmemory. The commands, further data and further memory address arecommunicated from Test Module 120 via M-Channel Interface 125 to IC 130.

Test Module 120 is further configured to receive (i.e., read) testresults from IC 130 and to process these received test results. In someembodiments, Test Module 120 is configured to report the results of thisprocessing to ATE 110. In some embodiments, Test Module 120 isconfigured to communicate a compressed version of the received testresults to ATE 110. Further details of Test Module 120 are discussedelsewhere herein.

IC 130 is an integrated circuit to be tested via Test Module 120. IC 130is not necessarily included as part of Test System 100 prior to testing.IC 130 is optionally a logic device such as an application specificintegrated circuit (ASIC), a processor, a microprocessor, amicrocontroller, a field programmable gate array (FPGA), a programmablelogic device (PLD), a complex programmable logic device (CPLD), or thelike. IC 130 may alternatively be implemented as an analog device, amodule, a circuit board, or a memory device, etc.

As a memory device, IC 130 can be an IC memory chip, such as, forexample, static random access memory (SRAM), dynamic random accessmemory (DRAM), synchronous DRAM (SDRAM), non-volatile random accessmemory (NVRAM), and read only memory (ROM), such as erasableprogrammable ROM (EPROM), electrically erasable programmable ROM(EEPROM), and flash memory, or any memory device operating under asuitable format or protocol, such as double-data rate (DDR) or DDR2. Thememory device can be configured in various configurations (e.g., X32,X16, X8, or X4) and may comprise a plurality of memory cells arranged,for example, in rows and columns. The memory cells can be implementedusing transistors, capacitors, programmable fuses, etc.

As a module, IC 130 can be a system-in-package (SiP), package-in-package(PiP), or system-on-chip (SoC). It also can be a combination of SoC, SiPand PiP. IC 130 may be disposed within suitable packaging, such as, forexample, as a standard ball grid array (BGA) or thin quad flatpack(TQFP). The packaging may further utilize various surface mounttechnologies such as a single in-line package (SIP), dual in-linepackage (DIP), zig-zag in-line package (ZIP), plastic leaded chipcarrier (PLCC), small outline package (SOP), thin SOP (TSOP), flatpack,and quad flatpack (QFP), to name but a few, and utilizing various leads(e.g., J-lead, gull-wing lead) or BGA type connectors.

Clock 140 is configured to provide a clock signal to Test Module 120 foruse in communicating between Test Module 120 and IC 130. Clock Signal140 is typically different from a clock signal used for communicatingbetween ATE 110 and Test Module 120. Thus, N-Channel Interface 115 mayoperate at a different (e.g., higher) frequency than M-Channel Interface125. The clock signal provided by Clock 140 is optionally a multiple ofthe clock signal used by ATE 110. Clock 140 can include a phase-lockedloop, a crystal oscillator, or the like. The clock signal received fromClock 140 is typically synchronized with the clock signal used by ATE110 using one of the various methods known in the art. Clock 140 isoptional when Test Module 120 is configured to generate a clock signal,for use in communication with IC 130, based on a clock signal receivedfrom ATE 110. For example, in some embodiments, Test Module 120 includeslogic configured to multiply a clock signal received from ATE 110 by afactor of 1.5, two or more.

FIG. 2 is a block diagram of Test Module 120, according to variousembodiments of the invention wherein IC 130 is a memory device. Theembodiments illustrated by FIG. 2 include several components configuredto communicate with ATE 110. These components include a Clock Manager202, a Command Unit 204, a Test Control 206, and Test DQs 208. Theembodiments illustrated by FIG. 2 also include several componentsconfigured to communicate with IC 130. These components include a ClockDriver 220, a Command Driver 222, an Address Driver 224, and a DataInterface 226. Together, these components perform functions similar tothose of a memory manager. Between those components configured tocommunicate with ATE 110 and those components configured to communicatewith IC 130, Test Module 120 includes an Address Generator 210, aPattern Generation Logic 214, Test Mode Registers 212, Write Data Logic216, and Data Read Logic 218. The components illustrated in FIG. 2 mayinclude software, hardware, firmware, or combinations thereof.

Clock Manager 202 is configured to receive a test clock (TCK) signalfrom, for example, ATE 110. This test clock signal is typically a clocksignal generated by ATE 110 for the purposes of testing an integratedcircuit. Clock Manager 202 is optionally also configured to receive aphase lock loop clock (PLLCK) clock signal from Clock 140. In responseto the TCK and/or PLLCK signals, Clock Manager 202 generates one or moreother clock signals (e.g., CK0, CK, CK\), some of which may have afrequency that is higher than the received test clock TCK signal. Assuch, Test Module 120 can be configured to test IC devices that operateat clock frequencies higher than the clock frequency of ATE 110. Thisallows IC devices to be thoroughly tested, for example, using older testequipment. The clock signals output from Clock Manager 202 may beprovided to other components within Test Module 120. These componentsinclude Clock Driver 220, Command Driver 222, Address Driver 224,Address Generator 210, Write Data Logic 216 and Data Read Logic 218. Theoutput of Clock Manager 202 can be communicated to IC 130 via ClockDriver 220.

Command Unit 204 is configured to receive various test functionalsignals (e.g., TCKE, TDQS, TCS\, TRAS\, TCAS\, TWE\, TBA[0:2], TA10),and to process or forward these functional signals to other componentswithin Test Module 120. For example, Command Unit 204 is configured forgenerating command signals to be passed to IC 130 via Command Driver222. These command signals include, for example, CKE, CS, RAS\, CAS\,WE, BA[0:2]. In another example, Command Unit 204 is configured toreceive data generation and address generation commands for use byPattern Generation Logic 214 and Address Generator 210, respectively.Further details of the operation of Address Generator 210 and PatternGeneration Logic 214 are described elsewhere herein.

In some embodiments, the test functional signals received by CommandUnit 204 include SET, LOAD, and CMD (Command). A 4-bit wide stream canbe registered using a CMD pin as the input data source and the SETsignal to register. For example, an Activate Row command can be a seriesof four serial bits b0011, a Read command can be b0101, and so on. Theserial bits can be registered on the positive edge of TCK signal whenthe SET signal is high. In one embodiment, four registers and a 2-bitcounter can be used to accept the CMD input.

Test Control 206 is configured to receive the TEST, SET and LOAD signalsfor placing the module into test mode, program test modes (or phases),and load or enable test addresses and/or test vectors. In addition, insome embodiments, Test Control 206 is further configured to store datascramble patterns, row address scramble patterns and column addressscramble patterns. As is described further herein, these patterns areused to generate test addresses and test data. Test Control 206 isconfigured to provide one or more output signals to Test Mode Registers212, which functions to store or forward the test codes, vectors,patterns, etc. for further processing or use as appropriate. Forexample, TEST, SET and LOAD signals may be used to convey an addressgeneration pattern from ATE 110 to Test Module 120. The addressgeneration pattern is stored in Test Mode Registers 212 and read byAddress Generator 210 when needed. Likewise, TEST, SET and LOAD signalsmay be used to convey a data scramble pattern from ATE 110 to Test ModeRegisters 212. This data scramble pattern is used by Write Data Logic216 and Data Read Logic 218 as further described herein.

Test DQs 208 are further configured to receive address data from ATE 110and to convey this address data to Address Generator 210 for use ingenerating additional addresses. Test DQs 208 are further configured toreceive test data signals (e.g., TDQ[0:7]), from ATE 110. The receivedtest data signals are processed or forwarded to other components withinTest Module 120. These test data signals are optionally used to generateadditional test data using Pattern Generation Logic 214 and Write DataLogic 216. For example, Write Data Logic 216 can use test data signalsreceived via Test DQs 208 to generate data signals (e.g., DQ[0:31]),which are then provided to IC 130 via Data Interface 226.

Test DQs 208 are configured to receive both actual test data and testmode commands from ATE 110. For example, when the SET command isreceived by Test Control 206 a test mode command will be expected atTest DQs 208. When a LOAD command is received by Test Control 206,actual test data is expected at Test DQs 208.

FIGS. 3A and 3B illustrate test mode commands, according to oneembodiment of the invention. These commands include Items 1 and 9 for NoTest; Items 2 and 3 for loading row addresses; Items 5 and 6 for settingrow counter least significant bits (LSB); Item 8 for setting row counterdirection; Items 10 and 11 for loading column addresses; Items 13 and 14for setting column counter LSB; and Item 16 for setting column counterdirection. In FIG. 3B, Items 18 and 19 are commands configured forloading MRS (mode register set) data; Item 23 is for reading a chipidentification; Item 26 is for loading data scrambling (generation)information; Item 27 is used to determine the form in which test resultsare reported from Test Module 120 to ATE 110; Item 30 is for loadingfurther data generation information; and Item 31 is for controllingaddress and data generation for a specific class of memory architecture.Test Module 120 may also be configured to support enhanced MRS commands,mobile MRS commands, or the like.

Row counter LSB and column counter LSB are used to determine which rowbits and which column bits are incremented first during addressgeneration. For example, if the second bit of the row address is set asa row counter LSB then the associated row address will be incremented bytwo. If the third bit of the row address is set as the row counter LSB,then the associated row address will be incremented by four. The set rowcounter to count down command is used to determine whether the rowaddress will be counted up or down. Setting of LSB to other than thefirst bit is optionally used when it is desirable to step to memoryboundaries.

Returning to FIG. 2, Test DQs 208 are also configured to convey testresults to ATE 110 from Test Module 120. For example, signals receivedfrom IC 130 via Data Interface 226 can be processed by Data Read Logic218 and provided to Test DQs 208 for communication to ATE 110. The datacommunicated to ATE 110 via Test DQs 208 can include the full testresults received from IC 130, a condensed version of the resultsreceived from IC 130, or a summary of the results (e.g., a pass or failindication). The form of the data communicated depends on test criteriastored in Test Mode Registers 212 via Test Control 206.

Address Generator 210 is configured to receive signals from ClockManager 202, Command Unit 204, Test DQs 208, and Test Mode Registers212. Using this received information, Address Generator 210 isconfigured to generate test addresses (e.g., A[0:15]) for communicationto IC 130 via Address Driver 224. These addresses are used to address IC130. For example, in some embodiments, these addresses are used todirect the loading of data, via Data Interface 226, into IC 130. Forexample, data written to IC 130 from Data Interface 226 may be stored,within IC 130, at an address written to IC 130 from Address Driver 224.As is further described herein, the addresses generated by AddressGenerator 210 are optionally also provided to Pattern Generation Logic214 for use in generating test data or interpreting data received fromIC 130.

In some embodiments, Address Generator 210 includes a sequence patterngenerator, such as that described in related U.S. application Ser. No.10/205,883 entitled “Internally Generating Patterns For Testing In AnIntegrated Circuit Device,” filed on Jul. 25, 2002, and related U.S.application Ser. No. 11/083,473 entitled “Internally Generating PatternsFor Testing In An Integrated Circuit Device,” filed on Mar. 18, 2005,both of which are assigned to the same assignee and incorporated byreference herein in their entirety.

FIG. 4 illustrates further details of Address Generator 210, accordingto various embodiments of the invention. In these embodiments, AddressGenerator 210 includes an MRS Register 410, a Row Address Generator 420,a Column Address Generator 430, and an optional A10 Generator 440, eachconfigured to provide data to a MUX 450. MUX 450 is controlled by a MUXControl 460, and may also receive input from a Precharge Control 470.

MRS Register 410 is configured to receive SET, LOAD, mode register set(MRS), and test address signals (TA[0:7]). Test address signals(TA[0:7]) are received through TDQ[0:7] of Test DQs 208. Row AddressGenerator 420, which receives the SET, LOAD, and TCNT signals and a rowcounter signal, is configured to generate a plurality of row addressesfor use in testing IC 130. Column Address Generator 430, which receivesthe SET, LOAD, and TCNT signals and a column counter signal, isconfigured to generate a plurality of column addresses for use intesting memory device 130. A10 Generator 440 is configured to receive aTA10 signal. The TA10 signal is used to separately control an A10 bit.The A10 bit is a bit found on some types of memory capable ofpre-charging. For example, if IC 130 is a DRAM, then the A10 Generator440 may be configured for generating a bit to enable a DRAMauto-precharge, All-bank command.

MUX (multiplexer) 450 is configured to receive and multiplex the outputsof the MRS Register 410, Row Address Generator 420, Column AddressGenerator 430, and A10 Generator 440, under the control of MUX Control460. The output of MUX 450 is an output of Address Generator 210 and isprovided to Address Driver 224 for communication to IC 130. In someembodiments, the output of MUX 450 is also provided to Write Data Logic216 and Data Read Logic 218 for generation and interpretation of testdata.

Address Generator 210 is typically configured to generate more than oneaddress for delivery to Address Driver 224 for each address receivedfrom ATE 110. For example, in some embodiments, Address Generator 210 isconfigured to receive a single base address from ATE 110 and generate ablock of addresses in response. In some embodiments, Address Generator210 is configured to generate two (the original plus one) address foreach address received. For example, for each even address received,Address Generator 210 may be configured to generate a corresponding oddaddress. In various embodiments, Address Generator 210 is configured togenerate 4, 8, 16, 32, 64, 128, or more addresses for each addressreceived from ATE 110. In some embodiments, Address Generator 210 isconfigured to generate addresses sufficient to reach a next addressboundary. For example, if the counting direction is up, the burst lengthis 4 and the first read address is at Col-0, then the column counterwill jump to Col-4 for the next read address and generate four addresses(Col-0 to Col-3).

In some embodiments, Test Module 120 is configured to provide memoryaddresses to IC 130 in response to a memory access command received fromATE 110. For example, when an Active command is received from ATE 110and scheduled to be communicated to IC 130, MUX Control 460 isconfigured to control MUX 450 such that address bits from Row AddressGenerator 420 will be communicated to Address Driver 224. TestingInterface 120 will send the Active command (CS/RAS/CAS/WE=0011) and theaccompanying address bits A[0:13] (for 512 Mb×8 DRAM) to a DRAM undertest (e.g., IC 130).

When a Read command is scheduled to be communicated, MUX Control 460will use MUX 450 to select address bits from Column Address Generator430 to be sent to Address Driver 224. Testing Interface 120 will sendthe Read command (CS/RAS/CAS/WE=0101) and the accompanying addressA[0:9] (512 Mb×8 DRAM) and A10 (for auto-precharge or noauto-precharge). Similar events occur for Write and Load Mode Registeroperations that involve sending address bits. The operation of MUXControl 460 is typically responsive to the type of command beingprocessed (e.g., Load Mode Register, Precharge, Active, Read, Write,Select, etc.).

In some embodiments, test column addresses can be incrementedindependently from the test row addresses. Row Address Generator 420 andColumn Address Generator 430 are optionally configured to internallygenerate sequences of numbers for use as addresses during testing.

Referring again to FIG. 2, Test Mode Registers 212 are configured tostore test mode data for use by Address Generator 210, PatternGeneration Logic 214, Write Data Logic 216 and Data Read Logic 218during testing. For example, Test Mode Registers 212 are configured toreceive a starting column address and/or a starting row address fromTest DQs 208, and to receive test mode commands (such as thoseillustrated in FIGS. 3A and 3B) under the control of Test Control 206.During testing, these and other values are read from Test Mode Registers212 in order to generate test addresses and test data.

In some embodiments, Test Mode Registers 212 are programmable using aTest Register Set command and programmed through test data signalsTDQ0-TDQ7 of Test DQs 208. In a test mode, the inputs for TDQ0-TDQ7signals can be used to read and write test data, set test mode codes,load row and column addresses, program row and column counter leastsignificant bits (LSB), set data scramble patterns, set data generationlogic, and load test data patterns, etc. In some embodiments, theregisters within Test Mode Registers 212 can be set anytime. In someembodiments, a SET command at Command Unit 204 is set in a high state toload test mode commands and test mode data into Test Mode Registers 212.

In some embodiments, all or part of data scramble patterns, row addressscramble patterns and column address scramble patterns are stored in aremovable memory. For example, these patterns may be included in anEPROM configured to be plugged into Test Module 120 or plugged into atest mounting board configured to support one or more instances of IC130. In these embodiments, the various scramble patterns can beprogrammed while external to Test Module 120. For example, in someembodiments, different EPROMs are programmed with different testingprotocols and one of the different EPROMs is selected to be plugged intoTest Module 120 depending on the protocol desired. In some embodiments,different EPROMs are programmed for testing different types of IC 130.In alternative embodiments, scramble patterns are included in removablememory other than EPROMs. For example, Test Mode Registers 212 can beincluded in ROM, FLASH, one time programmable logic, or the like.

Pattern Generation Logic 214, Write Data Logic 216 and Data Read Logic218 are configured for generating test data to be written to IC 130 andfor interpreting test results read from IC 130. As is further describedherein, the generated test signals may include more data than receivedfrom ATE 110, may be responsive to data patterns stored in theinterface, and/or be responsive to addresses, or the like. FIG. 5illustrates further details of the data paths used for writing data to,and reading data from, IC 130, according to various embodiments of theinvention.

In those embodiments illustrated in FIG. 5, Test DQs 208 include anInput Buffer 510, an Output Buffer 512, a Data In Register 514, and aData Out Register 516. These buffers are configured to receive data fromand send data to ATE 110, respectively. When data is received from ATE110, the output of Input Buffer 510 is stored in Data In Register 514.Likewise, when data is ready for delivery to ATE 110 it is stored inData Out Reg. 516 until read by ATE 110. In various embodiments, TestDQs 208 are configured to communicate 8, 16, or more bytes in parallel.

In those embodiments illustrated in FIG. 5, Data Interface 226 includesan Output Buffer 520, an Input Buffer 522, an Output Shift Register 524,and a Data Read Capture 526. Data to be written to IC 130 is collectedin Output Shift Register 524 and then passed through Output Buffer 520.Data read from IC 130 is passed through Input Buffer 522 and captured byData Read Capture 526. In typical embodiments, Data Interface 226 isconfigured to communicate data at a faster clock frequency than Test DQs208.

In those embodiments illustrated by FIG. 5, Write Data Logic 216includes a Data Write Register 530 and a MUX 535. Data Write Register530 is configured to receive, for example, 8-bit data from Data InRegister 514. The received data is expanded to generate additional datausing a data scramble pattern under the control of Pattern GenerationLogic 214 according to a data scramble pattern. In typical embodiments,several data are generated within Data Write Register 530 in parallel.For example, Data Write Register 530 may be configured to generate eightsets of data from eight original bits in parallel. These data arecommunicated to MUX 535. In various embodiments, MUX 535 receives 16,32, 64 or more bits of data for each byte of data received by Test DQs208 from ATE 110. Further details of the data generation process arediscussed elsewhere herein.

In those embodiments illustrated by FIG. 5, Data Read Logic 218 includesa MUX 545, an optional Data Read Register 540, and an optionalComparison Unit 550. In some embodiments, Data Read Register 540 and MUX545 are configured to perform the reverse of the process performed inWrite Data Logic 216. For example, MUX 545 is configured to receive datafrom Data Read Capture 526 and pass the received data to one or moreData Read Registers 540. Data Read Register 540 is configured to use thesame data scramble pattern as used by Data Write Register 530 tocompress the received data in a process that is the reverse of thatperformed by Data Write Register 530. If the data received by Data ReadRegister 540 from MUX 545 is the same as the data generated by DataWrite Register 530, then Data Read Register 540 will compress the datasuch that it is the same as that received by Data Write Register 530from Data In Register 514. In some embodiments, this compressed data ispassed directly to Data Out Register 516 for communication to ATE 110.In these embodiments, Comparison Unit 550 is optional.

Data Read Capture 526, MUX 545, Data Read Register 540, Comparison Unit550 and Data Out Register 516 form a data path for reading data from IC130 during testing. In some embodiments, the components in the read datapath are configured to receive external data signals (DQ[0:31]) from IC130, compress the signals into external test data signals (TDQ[0:7]),and return the external test data signals to the external test machine(e.g., ATE 110). In other embodiments, the components in the read datapath are configured to receive external data signals (DQ[0:30]) from IC130, to compare these signals with expected values, and to reportresults of these comparisons using part of TDQ[0:7].

The components in the data pathway configured to write data to IC 130(e.g., Data In Register 514, Data Write Register 530, Pattern GenerationLogic 214, MUX 535, and Output Shift Register 524) are configured toreceive external test data signals (TDQ[0:7]) from ATE 110, expand thesignals into external data signals (DQ[0:31]), and provide the externaldata signals to IC 130.

In some embodiments, the components of the write data path may receivebits of test data from the external test machine at the operatingfrequency of the test machine, generate multiple bits for each bit ofdata received from the test machine, and transmit the generated bits toIC 130 at the operating frequency of IC 130 (which can be higher thanthe frequency at which ATE 110 operates).

In one example, the components in the write data path may receive a bitof TDQ3 with a value of “1” from ATE 110 at a clock frequency of 100MHz, generate a string of bits “1111” from that received bit by merelyrepeating the value multiple times, and then provide the string of bitsto IC 130 as DQ1-DQ15 at a frequency of 200 MHz. In another example, thecomponents in the write data path may receive a bit of TDQ3 with a valueof “1” from ATE 110 at a clock frequency of 100 MHz, generate on-the-flya string of bits “0101” from the received bit, and then provide thegenerated string of bits to IC 130 as DQ8-DQ11 at a frequency of 400MHz. The generation of the string of bits of “0101” from a bit of “1” isaccomplished using Pattern Generation Logic 214 which, for example, mayinclude logic to “invert every odd bit” in a string of “1111.” In otherexamples, each bit received at TDQ[0:7] is used to generate a burst of 4bits, 8 bits, or more for each of DQ[0:31]. For example, a bit receivedat TDQ3 may be used to generate a burst of four bits at each of DQ12,DQ13, DQ14 and DQ 15. This burst of bits can include any of the possiblefour bit patterns, responsive to Pattern Generation Logic 214.

In one embodiment, the components of the read data path may receive bitsof test result from IC 130 at the clock frequency of IC 130, translatestrings of test result bits into a single bit, and provide the singletest result bit to ATE 110 at the clock frequency of ATE 110. In oneexample, the components in the write data path may receive a test resultbit string of “0011” for DQ16-DQ19 from IC 130 at a clock frequency of400 MHz. The write data path components reduce this string to a value ofeither “0” or “1” depending on whether the string matches an expectedtest result, and provides the single bit (“0” or “1”) to ATE 110 throughTDQ5.

The ability of Testing Interface 120 to “expand” data received from ATE110 and to “compress” data received from IC 130 provides a technicaladvantage in that IC 130 can be tested at its normal clock speed usinginstances of ATE 110 configured to operate at a lower clock speed.

In alternative embodiments, the compressed data generated by Data ReadRegister 540 is passed to Comparison Unit 550. In these embodiments,Comparison Unit 550 is configured to compare this data with a copy ofthe data received by Data Write Register 530 from Data In Register 514.Based on this comparison, Comparison Unit 550 is configured to output avalue indicating whether the compared data matched or not, e.g., whetherthe test “Passed” or “Failed.” Thus, if the data read from IC 130through Data Read Capture 526 is the same as the data written to IC 130through Output Shift Register 524, Data Out Register 516 will receive avalue indicating “Passed” from Comparison Unit 550. If the read data isnot the same as the written data, then Data Out Register 516 willreceive a value indicating “Failed” from Comparison Unit 550. Thecomparison made by Comparison Unit 550 may be performed in parallel orin series.

In some embodiments, the value indicating “Passed” is a copy of the dataoriginally received by Test Module 120 from ATE 110 and the valueindicating “Failed” is the complement of this data. In some embodiments,the data originally received by Test Module 120 is stored within TestModule 120 for this purpose. In some embodiments, the original data issent from ATE 110 to Test Module 120 twice so that it does not have tobe stored in Test Module 120. The second set of data is optionally alsoexpanded for use in comparison with data received from IC 130 byComparison Unit 550. In some embodiments, the value indicating “Passed”is some other value communicated from ATE 130 to Test Module 120 forthis purpose.

In some embodiments, Data Read Register 540 is optional and ComparisonUnit 550 is configured to receive data directly from MUX 545. In theseembodiments, the data that Comparison Unit 550 receives from Data WriteRegister 530 is a copy of the expanded output of Data Write Register 530that was provided to MUX 535, rather than the input received from DataIn Register 514. This copy of the expanded output is compared with thedata received from MUX 545. In these embodiments, Comparison Unit 550 isconfigured to make a comparison using expanded data rather thancompressed data. The output of Comparison Unit 550 reflects whether thecomparison found a match or not. In these embodiments, the data readfrom IC 130 through Data Read Capture 526 does not have to berecompressed. The copy of the expanded output of Data Write Register 530may have been stored within Test Module 120 or may be reproduced ondemand from the original data received from Data In Register 514.

In alternative embodiments, Comparison Unit 550 is configured to receivedata directly from Data Read Capture 526. In these embodiments,Comparison Unit 550 is configured to receive a copy of the output of MUX535 and to compare this data with that received from Data Read Capture526. In these embodiments, MUX 545 is omitted.

Pattern Generation Logic 214 includes the logic required to process(e.g., compress or expand) data within Data Write Register 530 and DataRead Register 540 according to a data scramble pattern. In someembodiments, the processing includes communication of the data to beprocessed to Pattern Generation Logic 214, for example, from Data WriteRegister 530. In these embodiments, the actual processing occurs withinPattern Generation Logic 214 and the results are communicated back tothe component from which the data to be processed was received.

In alternative embodiments, Pattern Generation Logic 214 is configuredto communicate a data scramble pattern, logical rules, or the like toData Write Register 530 and Data Read Register 540. In theseembodiments, the actual processing occurs at Data Write Register 530and/or Data Read Register 540. For example, a data scramble pattern maybe sent by Pattern Generation Logic 214 to Write Data Logic 216 and thisdata scramble pattern may be XOR'ed with the data received from Test DQs208 for generating the output of Write Data Logic 216.

In some embodiments, Pattern Generation Logic 214 is configured to beloaded with data scramble patterns (via Test DQs 208) during orimmediately prior to testing of IC 130. In alternative embodiments,Pattern Generation Logic 214 is pre-loaded with several data scramblepatterns and one of the data scramble patterns is selected during orimmediately prior to testing through the use of a test pattern number.

Pattern Generation Logic 214 is configured to receive data from CommandControl 204, Test Mode Registers 212, Test DQs 208, Clock Manager 202,and Address Generator 210. In some embodiments, the generation of testdata can be address dependent because Pattern Generation Logic 214receives data from Address Generator 210. For example, different datascramble patterns can be used for data to be written to ODD and EVEN(column and/or row) addresses. In one embodiment, the address dependencyof data generation is used in testing instances of IC 130 wherein thelogic of actual physical storage is address dependent. For example, somememory devices use a first voltage signal for storing data at ODD columnaddresses and an inverted form of the first voltage signal for storingdata at EVEN column addresses. Thus, the data 11111111 may be stored inactual physical storage as 10101010. Through address dependent datageneration, Testing Interface 120 can be configured to run test patternssuch that the actual physical storage is 11111111, 00000000, or anypermutation thereof.

FIG. 6 is a block diagram illustrating further details of Data WriteRegister 530, according to various embodiments of the invention. A testdata signal (TDQ) is received from ATE 110 at a clock frequency of ATE110 and stored in Data In Register 514. From Data In Register 514, theTDQ signal is provided to an Even Block 610 and an Odd Block 615. EvenBlock 610 is configured to generate components of output data to bestored at even addresses and an Odd Block 615 is configured to generatecomponents of the output data to be stored at odd addresses. Even Block610 and Odd Block 615 also receive a test invert bit signal (TINV0) fromPattern Generation Logic 214. If this signal is HIGH then one of thebits within either Even Block 610 or Odd Block 615 will be invertedrelative to the TDQ signal. Which bit is inverted is dependent on thestate of a burst address LSB signal (CA0). In some embodiments, bitsassociated with ODD addresses will be inverted when TINV0 is HIGH. EvenBlock 610 receives burst address LSB signal (CA0) and Odd Block 615receives the complementary signal (CAM) from Pattern Generation Logic214. CA0 is, for example, the LSB of the current column address. EvenBlock 610 and Odd Block 615 may be configured to generate theirrespective outputs in a serial manner using an XOR operation or acombination of latches and multiplexers. For example, a multiplexer maybe configured to select an inverted output or non-inverted output of thelatch responsive to CA0.

The outputs of Even Block 610 and Odd Block 615 are passed to an InvertBlock 620 and an Invert Block 625, respectively. Invert Block 620further receives an INV0 signal from Pattern Generation Logic 214, andInvert Block 625 further receives an INV1 signal from Pattern GenerationLogic 214. Each of Invert Block 620 and Invert Block 625 are configuredto invert or not invert the outputs of Even Block 610 and Odd Block 615,responsive to INV0 and INV1, respectively. For example, in someembodiments, when INV0 or INV1 are HIGH, the incoming data is inverted.

Invert Block 620 and Invert Block 625 are configured to output thesignals data write even (DW_E) and data write odd (DW_O), which areprovided to a Register Block 630. In some embodiments, when the INV0 andINV1 signals are HIGH, the DW_E and DW_O signals will each include boththe original values and the complements of the outputs of Even Block 610and Odd Block 615, respectively. When the INV0 and INV1 signals are LOW,the DW_E and DW_O signals will each include two copies of the originalvalues of the output of Even Block 610 and Odd Block 615. The states ofthe INV0 and INV1 signals are dependent on the logic within PatternGeneration Logic 214 and, if Pattern Generation Logic 214 is programmedfor a specific instance of IC 130, these states can be dependent on thearchitecture and topology of IC 130.

As is discussed elsewhere herein, the operation of Pattern GenerationLogic 214 can be responsive to row address and/or column address. Forexample, in some embodiments, the following logic may be used to write asolid pattern in a memory array within IC 130: INV0=(RA0 XOR RA1) xorRA8. (Where RA0, RA1 and RA8 are row address bits, and XOR is theExclusive OR function.) This means that when row address RA0=1 and RA1=0and RA8=0, then INV0 will have a value of 1 data will be inverted inInvert Block 620. This inversion is optionally used to compensate formemory whose actual logical bit storage is address dependent. In mostcases, INV0 will be the same as INV1, and therefore only one signal isrequired.

Typically, Data Write Register 530 will include a similar set ofcomponents configured to process each TDQ data element received from ATE110 (e.g., TDQ0 through TDQ7). For example, if TDQ0 is equal to 1, CA0(LSB of column address) is 0, and TINV0 is 1, then the input to InvertBlock 620 will be 1 and the input to Invert Block 625 will be 0.(TINV0=1 means invert odd bit is active). Invert Block 620 and InvertBlock 625 will invert the data again if the INV0 or INV1 signals areactive. The value of the INV0 or INV1 signal depends on the output ofPattern Generation Logic 214.

In some embodiments, Register Block 630 includes a plurality offirst-in-first-out (FIFO) registers configured to receive DW_E and DW_O.As illustrated in FIG. 6, these FIFO registers can include EV_0 Register635, EV_1 Register 640, OD_0 Register 645, and OD_1 Register 650. EV_0Register 635 and EV_1 Register 640 are configured for processing datareceived from Invert Block 620 and to be included in even bits of theoutput of Test Module 120, while OD_0 Register 645 and OD_1 Register 650are configured for processing the corresponding odd bits. EV_0 Register635 and EV_1 Register 640 are configured to store data write even 0(DW_E0) and data write even 1 (DW_E1) signals from the DW_E signal. OD_0Register 645 and OD_1 Register 650 are configured to store data writeodd 0 (DW_O0) and data write odd 1 (DW_O1) signals from the DW_O signal.These DW_E0, DW_E1, DW_O0, and DW_O1 signals are provided in parallel toMUX 535. MUX 535 is configured to generate a serial stream from theseparallel signals. The serial stream is provided to IC 130 as a sequenceof data (e.g., 4 bits) in a data signal (DQ) via Output Shift Register524. Thus, in the embodiments illustrated by FIG. 6, one bit of TDQ datafrom ATE 110 results in 4 bits of DQ data conveyed to IC 130.

As previously described in U.S. patent application Ser. No. 11/207,581entitled “Architecture and Method for Testing of an Integrated CircuitDevice,” components similar to those illustrated in FIG. 6 may beincluded in the read data path of Testing Interface 120. In someembodiments, if the test data provided to IC 130 is the same as thatreceived from IC 130, then Test Module 120 is configured to pass back toATE 110 the same data that Test Module 120 originally received from ATE110, and if the data received from IC 130 is not the same as thatprovided to IC 130, then Test Module 120 is configured to pass to ATE110 the complement of the data that Test Module 120 originally receivedfrom ATE 110.

FIG. 7A and FIG. 7B include tables illustrating several examples of dataexpansion using the systems illustrated by FIG. 6. These tables includea TDQ Column 710 representing data bits received from Data In Register514, a CA0 column 720 indicative of the CA0 and CA0\ values received byEven Block 610 and Odd Block 615, and an Even Data Bit Column 730representative of whether the first bit is associated with an even orodd address. The tables further include a Four-Part Column 740indicative of the outputs of Register Block 630 (e.g., DW_E0, DW_E1,DW_O0, and DW_O1). In FIG. 7A Four-Part Column 740 is representative ofa default mode wherein TINVO is LOW, and in FIG. 7B Four-Part Column 740is representative of a default mode wherein TINVO is HIGH. Finally, thetables included in FIGS. 7A and 7B include a Four-Part Column 750representative of the four DQ output values provided to Output ShiftRegister 524.

FIGS. 8A-8H illustrate a variety of test data patterns that may bedelivered to IC 130 from Test Module 120, according to variousembodiments of the invention. FIGS. 8A and 8B include test data patternsthat result in uniform arrays of bits, e.g., all 1 or all 0. FIGS. 8Cand 8D include test data patterns having single inversions, e.g., everyother bit is inverted. FIGS. 8E and 8F include test data patterns havingdual inversions, e.g., every other pair of bits is inverted. And FIGS.8G and 8H include test data patterns having quad inversions, e.g. everyother set of four bits is inverted. Other test data patterns result incheckerboard, column stripe, row stripe, double column, double row, orsimilar bit storage within IC 130.

The actual physical storage pattern of test data that occurs in IC 130may be different from the bit pattern provided to IC 130. For example,some types of memory storage use different tables for even and oddcolumn addresses. In these memories, the test data pattern of FIG. 8Cmay result in a table of all ones corresponding to the even columnaddresses and a table of all zeros corresponding to the odd columnaddresses (assuming the first bit of the pattern is destined for an evencolumn address). If the test data pattern of FIG. 8D were used, thefirst table would be all zeros and the second table would be all ones.Further, in these memories, the test data patterns of FIGS. 8E and 8Fresult in a checkerboard pattern within each of the two tables.

In some memories, as discussed elsewhere herein, some types of memoryemploy an architecture wherein the logic of actual physical storage ofdata is address dependent. For example, a logical 1 may be representedby a HIGH voltage in even address columns (and/or rows) and by a LOWvoltage in odd address columns (and/or rows). In these types of memory,the data test patterns of FIGS. 8A and 8B result in a checkerboard ofvoltage values, while the test data patterns of FIGS. 8C and 8D resultin an array of memory cells filled with the same actual voltage values.Because the generation of test data within Test Module 120 can be columnaddress and/or row address dependent, Test Module 120 is capable ofapplying desirable test patterns to types of memory wherein the actualphysical storage is address dependent.

Returning to FIG. 2, Clock Driver 220 is configured to provide a clocksignal to IC 130. This clock signal is typically generated using ClockManager 202 and may be faster than a clock frequency received from ATE110.

Command Driver 222 is configured to convey commands received fromCommand Control 204 to IC 130. For example, Command Driver 222 may beconfigured to provide LOAD, READ, PRECHARGE or similar commands to aninstance of IC 130 that includes a memory device. In some embodiments ofthe invention, Command Driver 222 includes a scheduler configurable tocontrol the timing of commands (or data) communicated from Test Module120 to IC 130. For example, it may be desirable to test the ability ofIC 130 to accept commands at a predefined rate.

FIG. 9 illustrates an embodiment of Command Driver 222 configured toschedule delivery of commands to IC 130. This embodiment includes a setof D-FFs (flip-flops) 920, a FIFO (first-in-first-out) Buffer 930, aCommand Decoder 940, a Schedule Counter 950, and a State Machine 960.D-FFs 920 are asynchronous flip-flops configured for synchronizingdelivery of commands received through Command Control 204 at thefrequency of ATE 110 (TCK) with the clock frequency of Test Module 120(CK0). CK0 may be two or more times greater than TCK. Synchronizationwith as few as two D-FFs is possible in embodiments where CK0 issynchronized with TCK by Clock Manager 202.

FIFO Buffer 930 is configured to store commands received from D-FFs 920until the commands are ready for communication to IC 130. FIFO Buffer930 can be, for example a 16 deep FIFO buffer. Commands are also decodedin Command Decoder 940 and passed to Schedule Counter 950. ScheduleCounter 950 determines, using a table lookup, how may clock cyclesshould be allowed to pass between a particular command and the precedingcommand. The preceding command is optionally read by Schedule Counter950 from FIFO Buffer 930. When a command is POPed from FIFO Buffer 930,it is received by State Machine 960, which is configured to wait thenumber of clock cycles determined by Schedule Counter 950 beforeconveying the command to IC 130.

Programmed delays can be set in terms of clock ticks. Thus, somecommands may cause a delay of 1, 2, 3, 4, or more clock ticks before thenext command is communicated to IC 130. Actual delay times betweencommands can be controlled by setting a delay in terms of clock ticks orby changing the frequency of the clock used for communication betweenTest Module 120 and IC 130.

FIG. 10 includes a table illustrating clock cycle based commandscheduling, according to various embodiments of the invention. Withinthis table, a Parameter Column 1010 includes several different commandsets as may be defined in State Machine 960. For example, the timingcharacteristics of an Active command, followed by a Read/Write command,are shown in the third row. The default clock period (tCK) is 3.75nanoseconds (ns) while other times are expressed as multiples of tCK.Typically, tCK is the clock period used for communication between TestModule 120 and IC 130. The data shown is applicable to a specific typeof SDRAM (Synchronous Dynamic Random Access Memory). Other clock speedsand delays may be used in alternative embodiments. Scheduling can alsobe employed, for example, to reduce the effects of latency within TestModule 120.

Referring again to FIG. 2, Address Driver 224 is configured to provideaddresses to IC 130. Typically, these addresses are for reading orwriting data through Data Interface 226. Data Interface 226 isconfigured to convey data between Testing Interface 120 and IC 130. Insome embodiments, Data Interface 226 includes test pads, contact pins,sockets, or the like, configured for making electrical contact with IC130.

FIG. 11 illustrates a Test Mounting Board 1110 including at least oneTest Module 120 and at least one Mount 1120 configured to receive IC130, according to various embodiments of the invention. Test MountingBoard 1110 can include a printed circuit board module, or the like. Insome embodiments, Test Module 120 is implemented as a 10×10 mm 144 pinbinary gate array (BGA) and Mount 1120 is an SDRAM BGA socket.

FIG. 12 illustrates a Test Array 1210 including a plurality of TestMounting Boards 1110, according to various embodiments of the invention.In various embodiments, Test Array 1210 includes 2, 4, 8, 16, 32 or moreof Test Mounting Boards 1110. Test Array 1210 further optionallyincludes a Memory 1220 configured to store test parameters andelectronically coupled to each of the Test Mounting Boards 1110. Forexample, in various embodiments, Memory 1220 includes a data scramblepattern, a column address scramble pattern, a row address scramblepattern, other testing parameters, and/or the like. Memory 1220 istypically a non-volatile memory such as a static RAM or FLASH. Memory1220 is optionally detachable.

FIG. 13 illustrates methods of testing IC 130 using Test Module 120,according to various embodiments of the invention. In these methods,Test Module 120 is connected to ATE 110 and IC 130, and configured toperform tests specific to IC 130. These tests include Test Module 120receiving test signals from ATE 110, generating test addresses and testdata based on the receive test signals, sending the generated testsignals to IC 130, receiving test results from IC 130, and reportingback to ATE 110.

More specifically, in an Attach ATE Step 1310, Test Module 120 iselectronically coupled to ATE 110 through N-Channel Interface 115. Insome embodiments, this coupling includes connecting Test Module 120 to astandard test probe included in ATE 110. In some embodiments, thiscoupling includes coupling ATE 110 to a printed circuit board on whichTest Module 120 is mounted.

In an Attach IC Step 1320, Test Module 120 is electronically coupled toone or more integrated circuits to be tested, e.g., IC 130. Thiscoupling may take place through M-Channel Interface 125 and/or TestArray 1210. For example, in some embodiments, Attach IC Step 1320includes plugging a plurality of ICs 130 into Mounts 1120 within TestArray 1210. In some embodiments, this plurality of ICs 130 includes aplurality of memory devices.

In a Configure Test Module Step 1330, Test Module 120 is configured toperform tests on IC 130. The configuration may include designation of aclock frequency for communicating with IC 130 that is different from aclock frequency used for communications between ATE 110 and Test Module120. The configuration can further include specification of parametersfor generating test addresses and test data within Test Module 120 foruse in testing IC 130. In some embodiments, configuring Test Module 120includes selecting of one of several alternative predetermined testingconfigurations. In some embodiments, configuring Test Module 120includes coupling a non-volatile memory, having stored therein testingparameters, to Test Module 120. In some embodiments, Configure TestModule Step 1330 includes communicating configuration commands and datafrom ATE 110 to Test Module 120. These data are optionally stored inTest Mode Registers 212.

Configure Test Module Step 1330, Attach IC Step 1320 and Attach ATE Step1310 are optionally performed in alternative orders.

In a Receive Signals Step 1340, Test Module 120 receives signals fromATE 110 through N-Channel Interface 115. These signals are received at afirst clock frequency and may include commands for IC 130, addresses andtest data. Typically, the received test signals are dependent on a setupof ATE 110.

In a Generate Step 1350, Test Module 120 is used to generate testaddresses and test data responsive to the signals received in ReceiveSignals Step 1340 and the configuration specified in Configure TestModule Step 1330. Generate Step 1350 typically includes use of AddressGenerator 210 to generate test addresses, and use of Pattern GenerationLogic 214 and Write Data Logic 216 to generate test data.

In various embodiments, Generate Step 1350 results in 2, 4, 6, 8 or moredata elements for each data element received from ATE 110 in ReceiveSignals Step 1340. Generate Step 1350 optionally includes generation oftest data responsive to address data. For example, the generationprocess may be different for data to be stored at an EVEN address ascompared to data to be stored at an ODD address. The generated test datais optionally configured to result in a specific data pattern within IC130. These patterns may include all ones, all zeros, checkerboard,inversion of every other bit, inversion of every other bit pair,alternative columns or alternative rows, or the like.

In a Send Test Signals Step 1360, test data generated in Generate Step1350 are sent from Test Module 120 to IC 130, for example, usingM-Channel Interface 125 and at a second clock frequency. The secondclock frequency is optionally faster than the first clock frequency. Insome embodiments, Send Test Signals Step 1360 includes scheduling of thedelivery of commands from Test Module 120 to IC 130.

In an optional Receive Results Step 1370, test results are received byTest Module 120 from IC 130, for example, via M-Channel Interface 125.These test results are in response to the test signals sent in Send TestSignals Step 1360.

In an optional Report Step 1380, the received test results are processedby Test Module 120 and a report is provided to ATE 110. In someembodiments, this processing includes an inverse of the data generationprocess used in Generate Step 1350. In some embodiments, this processingincludes comparing the received test results with expected test results.The report provided to ATE 110 can include data indicating “Pass” or“Fail,” the data expected by ATE 110 or the complement of this data, orthe like.

In an optional Detach IC Step 1390, IC 130 is detached from Test Module120. Typically, IC 130 is configured to operate in a normal modeseparate from Test Module 120. Test Module 120 is configured to receivedifferent instances of IC 130 and to repeat the methods illustrated byFIG. 13 on each instance.

FIG. 14 illustrates methods of generating test data, according tovarious embodiments of the invention. These methods may be included in,for example, Generate Step 1350 of FIG. 13. In the methods illustrated,data generation is responsive to the configuration of Test Module 120 asdetermined in Configure Test Module Step 1330, as well as addresses andtest data received from ATE 110.

In a Receive Input Step 1410, Test Module 120 receives test data, andoptionally a test address, from ATE 110. The received test data caninclude a single bit, an 8-bit byte, a 16-bit word, a pair of 8-bitbytes, or the like. The received data is optionally stored in an inputbuffer, such as Data In Register 514. This test data is received at afirst clock frequency.

In an optional Address Based Inversion Step 1420, a bit of the datareceived in Receive Input Step 1410 is duplicated. This duplicationresults in two instances of the bit (the original and the new instance).One, both or neither of the two instances are then inverted responsiveto address data. For example, in some configurations of Test Module 120the copy of the bit to be stored at an even address is inverted and thecopy to be stored in an odd address is not inverted.

Address Based Inversion Step 1420 is optionally performed using EvenBlock 610 and Odd Block 615 as illustrated in FIG. 6. Address BasedInversion Step 1420 is typically applied in parallel to each bit of datareceived in Receive Input Step 1410. Address Based Inversion Step 1420results in a doubling of the number of test data bits.

In a Pattern Based Inversion Step 1430, each available test bit isduplicated to generate two instances of that bit. One, both or neitherof the two instances are then inverted in response to a test pattern.For example, in some embodiments, Invert Block 620 and Invert Block 625are each used to duplicate a bit and invert the new instance of that bitresponsive to INV0 and INV1, respectively. INV0 and INV1 are receivedfrom Pattern Generation Logic 214. The results of Pattern BasedInversion Step 1430 are optionally stored in a latch or a register blocksuch as Register Block 630.

Address Based Inversion Step 1420 and Pattern Based Inversion Step 1430are optionally performed in different orders. Together these stepsresult in a quadrupling of the available test data. For example, 8 bitsof test data received from ATE 110 will result in 32 bits of availabletest data. In some embodiments, one or both of these steps are performedadditional times in order to generate further data.

In a Serialize Step 1440, bits generated using Address Based InversionStep 1420 are serialized using a multiplexer, such as MUX 535. Theserialization process results in an ordered sequence of bits. Thisordered sequence is optionally stored in Output Shift Register 525.

In a Deliver Step 1450, the ordered sequence of bits is delivered to anintegrated circuit being tested, e.g., IC 130. This delivery is at asecond clock frequency, which is optionally different (e.g., faster orslower) than the first clock frequency of Receive Input Step 1410.

FIG. 15 illustrates methods of processing test results received from IC130, according to various embodiments of the invention. In theseembodiments, the test results are subject to an approximate inverse ofthe data generation process discussed, for example, in relation to FIG.14.

In a Receive Test Result Step 1510, Test Module 120 receives data fromIC 130. This data is responsive to test data previously provided to IC130, for example through the methods illustrated in FIGS. 13 and 14. Insome instances, the data may be received in response to a READ commandsent to IC 130. The received data is received at a first clockfrequency.

In a Serial Compress Step 1520, the received data is serially compressedbased on inversion signals received from Pattern Generation Logic 214.For example, in some embodiments, the received data is compressedresponsive to INV0 and INV1 signals. Serial Compress Step 1520 reducesthe number of bits included in the received data by a factor of twotimes, and may be performed using an inverse of invert Block 620 andInvert Block 625.

In an optional Serial Compress Step 1530, received data is furthercompressed in response to address information. For example, datareceived from an ODD address may be compressed using different logicthan data received from an EVEN address. Serial Compress Step 1530 maybe performed using an inverse of Even Block 610 and Odd Block 615, andresult in a further reduction of the data by a factor of two times.

Serial Compress Step 1520 and Serial Compress Step 1530 are optionallyperformed in alternative orders. Together, these steps result in acompression of the received data by a factor of four. For example, if 32bits are received from IC 130, these steps will result in 8 bits ofcompressed data. Either of these steps may be repeated in order toachieve greater compression ratios.

In a Report Step 1540, the compressed data generated using SerialCompress Step 1520 and Serial Compress Step 1530 is communicated to ATE110. This communication is optionally at a different clock frequencythan the first clock frequency.

FIG. 16 illustrates alternative methods of processing test resultsreceived from IC 130, according to various embodiments of the invention.In these embodiments, the test results are compared with an expectedresult and an output of this comparison is used to communicate to ATE110. The comparison can be made with data as it is received from IC 130,with the data received from IC 130 following one compression step (e.g.,Serial Compress Step 1520 or Serial Compress Step 1530), or with thedata received from IC 130 following more than one compression step. Thecommunication to ATE 110 can include a value indicating “Passed” or“Failed,” or alternatively the data expected by ATE 110.

In a Receive Test Result Step 1610, Test Module 120 receives data fromIC 130. This data is responsive to test data previously provided to IC130, for example through the methods illustrated in FIGS. 13 and 14. Insome instances, the data may be received in response to a READ commandsent to IC 130. The received data is received at a first clockfrequency.

In an Access Expected Result Step 1620, Test Module 120 accesses anexpected result. The expected result may be different depending onwhether the data received in Receive Test Result Step 1610 is be tocompressed prior to comparison with the expected result. For example, ifthe received data is to be compared prior to any compression, then theexpected result may be a copy of data sent from Test Module 120 to IC130, e.g., in Report Step 1380 or Deliver Step 1450. This copy may havebeen previously stored in Test Module 120 or may be regenerated whenneeded as part of Access Expected Result Step 1620. In another example,if the received data is to be compared following one or more compressionsteps, then the expected data may be a copy of data at an appropriatestage of the methods illustrated by FIG. 14. This copy may have beenpreviously saved or may be reproduced on the fly from data originallyreceived from ATE 110, e.g., in Receive Input Step 1410.

In some embodiments, Access Expected Result Step 1620 includes receivingan expected result from ATE 110. For example, an expected result may beloaded into Test Module 120 from ATE 110 using Test DQs 208 and acommand specific to this operation. These embodiments may beadvantageous when the result received back from IC 130 is expected to bedifferent from those sent to IC 130. In some embodiments, loading of anexpected result from ATE 110 to Test Module 120 includes using aspecific Expected Data Load command or a dedicated input.

In a Compare Step 1630, Comparison Unit 550 is used to compare theexpected result accessed in Access Expected Result Step 1620 with thedata received from IC 130 (or a compressed version thereof).

In a Report Step 1640, the output of the comparison made in Compare Step1630 is used for communicating with ATE 110. In some embodiments, theoutput is used to determine if a value indicating “Failed” or “Passed”should be sent to ATE 110. In some embodiments, a copy of the expecteddata is sent to ATE 110 if the output of Compare Step 1630 indicatesthat the expected data was received from IC 130, and the complement ofthe expected data is sent to ATE 110 if the output of Compare Step 1630indicates that the expected data was not received from IC 130.

The methods illustrated by FIG. 15 and FIG. 16 are optionally used invarious combinations. For example, one compression step may be followedby a comparison with expected data. The report provided to ATE 110 fromIC 130 is optionally provided at a different frequency than the datareceived by Test Module 120 from IC 130.

FIG. 17 illustrates methods of generating address data, according tovarious embodiments of the invention. These methods may be performed,for example, using Address Generator 210.

In a Set Row Counter Step 1710, an initial value of a row counter is setwithin Test Module 120. This initial value may be loaded into TestModule 120 using Test DQs 208 and an appropriate command at CommandControl 204. Alternatively, this initial value may be loaded into TestModule 120 by coupling a non-volatile memory to Test Module 120, thenon-volatile memory having the initial value pre-loaded. In someembodiments, the initial row value is configured to indicate a memoryaddress within IC 130 at which initial test data will be stored.

In a Set Column Counter Step 1720, an initial value of a column counteris set within Test Module 120. This step can be performed in mannerssimilar to that of Set Row Counter Step 1710. In some embodiments, theinitial column value is configured to indicate a memory address withinIC 130 at which initial test data will be stored.

In a Set Row Count Direction Step 1730, a row count direction is setwithin Test Module 120. This step can be performed in manners similar tothat of Set Row Counter Step 1710. The count direction can be “positive”for counting up or “negative” for counting down.

In a Set Column Count Direction Step 1740, a column count direction isset within Test Module 120. This step can be performed in mannerssimilar to that of Set Row Counter Step 1710. The count direction can be“positive” for counting up or “negative” for counting down.

In a Set Row LSB Step 1750, an LSB (least significant bit) for rowcounting is set. This step can be performed in manners similar to thatof Set Row Counter Step 1710. The LSB is the bit that will be changedfirst in the counting process. If the lowest value bit is the LSB, thencounting will occur by one. If the next bit is set as the LSB, thencounting will occur by two, and if the next bit after that is set as theLSB, then counting will occur by 4, etc.

In a Set Column LSB Step 1760, an LSB for column counting is set. Thisstep can be performed in manners similar to that of Set Row Counter Step1710. In a Count Row Step 1770, a row address is changed responsive tothe values set in Steps 1710, 1730 and 1750. In a Count Column Step1780, a column address is changed responsive to the values set in Steps1720, 1740 and 1760. In a Serialize Address Step 1790, the changedcolumn address and the changed row address are serialized to form acomplete address that may be used to access IC 130.

In various embodiments, one or more of the steps illustrated in FIG. 17are optional. For example, by default count directions may be alwayspositive, the row and/or column LSBs may always be the lowest value bit,and the initial values of the row and/or column counters may be equal tozero or one.

FIG. 18 illustrates methods of command scheduling, according to variousembodiments of the invention. In these methods, commands are received byTest Module 120 for delivery to IC 130. These commands are typicallyreceived from ATE 110 at a different (e.g., slower) clock frequency thanthey are delivered from Test Module 120 to IC 130. In order to controlthe timing of delivery of the commands to IC 130, the commands may betemporally held in Test Module 120 and delivered according to a deliveryschedule. The methods illustrated by FIG. 18 allow a user of Test Module120 to test the ability of IC 130 to receive and respond to commands atspecific rates.

In a Receive Command Step 1810, Test Module 120 receives a command fromATE 110. The received command may include, for example, a Read command,a Write command, an Active command, a Refresh command, a Prechargecommand, or the like.

In a Store Command Step 1820, the received command is stored. In someembodiments, the command is stored in a FIFO buffer, e.g., FIFO Buffer930, following temporary storage in a D-flip-flop. The D-flip-flop,e.g., D-FFs 920, is typically running at a second clock frequencysynchronized with the first clock frequency. In some embodiments, thesecond clock frequency is at least two times greater than the firstclock frequency. In various embodiments, the FIFO buffer is configuredto store 4, 8, 16, 32 or more commands.

In a Determine Command Delay Step 1830, the delay required for thereceived command is determined. The amount of delay is typicallymeasured in clock cycles of the second clock frequency. The amount ofdelay is optionally dependent on a previously received command. Forexample, a delay between a Precharge command and a Read command may bedifferent from a delay between a Read command and a Precharge command.Further examples of command delays are illustrated in FIG. 10.

In some embodiments, Determine Command Delay Step 1830 includes usingCommand Decoder 940 to decode the received command and Schedule Counter950 to determine a proper delay. Schedule Counter 950 is typicallyconfigured to look up delay times in a table similar to that shown inFIG. 10. This data is optionally stored within Test Module 120 or in amemory accessible to Test Module 120. Schedule Counter 950 is configuredto receive the preceding command from FIFO Buffer 930.

In a Retrieve Command Step 1840, the command received from ATE 110 isPOPed from FIFO Buffer 930 and loaded into State Machine 960.

In a Delay Step 1850, the received command is held in State Machine 960until the proper delay time has passed, as determined by an input fromSchedule Counter 950. In a Deliver Step 1860, following the proper delaytime, the received command is passed from Test Module 120 to IC 130.

FIG. 19 illustrates methods of configuring a test array for testing aplurality of integrated circuits, according to various embodiments ofthe invention. In these methods, a test array, such as Test Array 1210,is loaded with testing parameters configured to be used for testing morethan one instance of IC 130. In some embodiments, testing parameters areloaded into Test Array 1210 by insertion of a non-volatile memoryincluding a testing procedure. In other embodiments, testing parametersare loaded into Test Array 1210 by communicating a testing procedure(with associated testing parameters) into Test Array 1210. The testingparameters are optionally stored in an instance of Test Mode Registers212 shared by a plurality of Test Modules 120.

In a Select IC Step 1910, an integrated circuit, e.g., IC 130, isselected for testing. This selection may include, for example, selectionof a specific type of integrated circuit from a particular manufacturer.

In a Select Procedure Step 1920, a testing procedure is selected fortesting the selected integrated circuit. The testing procedure istypically one of several alternative testing procedures configured forthe selected integrated circuit or for different integrated circuits.Each of the alternative testing procedures is associated with a set oftesting parameters. These parameters include data that, as discussedelsewhere herein, may be stored in Test Mode Registers 212. Theseparameters may also include delay data, such as that illustrated in FIG.10, for use in scheduling delivery of commands to IC 130.

In an Insert IC Step 1930, one or more instances of the integratedcircuit selected in Select IC Step 1910 are inserted into Test Array1210. For example, in some embodiments, several instances of a memorychip are inserted into corresponding instances of Mount 1120 within aplurality of Test Mounting Boards 1110 within Test Array 1210.

In a Program Procedure Step 1940, the testing parameters characterizingthe selected testing procedure are loaded into Test Array 1210. In someembodiments, the programming procedure includes inserting a non-volatilememory including the testing parameters into Memory 1220. In otherembodiments, the programming procedure includes communicating thetesting parameters to Memory 1220 after Memory 1220 has been inserted inTest Array 1210. Memory 1220 is configured to be shared by a pluralityof instances of Test Module 120 within Test Array 1210. In otherembodiments, the programming procedure includes communicating inparallel to each of several instances of Test Module 120 such that thetesting parameters are loaded into a plurality of associated Test ModeRegisters 212.

In an optional Test IC Step 1950, one of the integrated circuitsinserted into Test Array 1210 is tested using automated testingequipment and the testing parameters loaded into Test Array 1210 inProgram Procedure Step 1940.

FIG. 20 illustrates embodiments of the invention wherein Test Module 120is configured to test a plurality of IC 130 in parallel. In theseembodiments, the outputs of Clock Driver 220, Command Driver 222,Address Driver 224, and/or Data Interface 226 are provided to more thanone instance of IC 130 in parallel. For example, the generated dataoutputs of Data Interface 226 (e.g., DQ[0:31]) may be divided among fourseparate IC 130, the first IC 130 receiving DQ[0-7], the second IC 130receiving DQ[8-15], the third IC 130 receiving DQ[16-23], and the fourthIC receiving DQ[24-31]. The outputs of Clock Driver 220, Command Driver222, and/or Address Driver 224 are also distributed to each of the fourseparate IC 130, each IC 130 typically receiving the same data fromthese components.

In some embodiments, each of the plurality of IC 130 illustrated in FIG.20 is disposed within the same electronic device. For example, each IC130 may be a separate memory chip within a SiP. Alternatively, each ofthe plurality of IC 130 illustrated in FIG. 20 may be disposed inseparate electronic devices. For example, each of the plurality of IC130 mounted on a different Test Mounting Board 1110 within Test Array1210. In the embodiments of Test Module 120 illustrated in FIG. 20, ATE110 can be used to test 2, 3, 4 or more IC 130 in the time it would taketo test one IC 130 without the use of Test Module 120. Further, evenwhen more than one IC 130 is tested in parallel, the testing can be at aclock frequency higher than that of ATE 110.

FIG. 21 illustrates Logic, generally designated 2100 and used in serialcompression following reading of data from IC 130. Serial compression isaccomplished using expected data received from ATE 110 and optionallydata scramble information received from Pattern Generation Logic 214.The expected data is optionally communicated to Test Module 120 from ATE110 at the same time as test (TDQ) data. In some embodiments, theexpected data is communicated through one or more additional data pins.For example, in some embodiments N-Channel Bus 115 includes twoconnections to pins of Test Module 120 configured for conveying expecteddata. In some embodiments, expected data is multiplexed through commandpins. These embodiments may be applicable to testing of DDR memory orother devices that include an extra clock cycle following a command.

The compression performed by the Logic 2100 illustrated in FIG. 21 isserial in that bits used in the compression are received and processedin a serial manner, and also in that the compression takes place in twostages. A first stage in which Logic 2100 is applied is, in part,dependent on whether the first data received is from an even address oran odd address, and a second stage wherein the logic applied is, inpart, dependent on results from neighboring bit pairs. The first stageincludes Logic Gates 2120 divided into two sets, generally designated2110A and 2110B, and configured to generate an output dependent on theexpected data and the actual data received. The expected data isrepresented by enable match values EM00, EM11, EM01, and EM10. EM00 isto enable match “0,0” with an expected output of “0,”,EM11 is to enablematch “1,1” with expected output “1,” EM01 is to enable match “0,1” withan expected output “0,” and EM10 is to enable match “1,0” with anexpected output “1.” Typically, the EM00, EM11, EM01, and EM10 inputsare used by applying these values, as received in expected data from ATE110, to the inputs of NAND, AND, or OR gates within Logic Gates 2120.EM01 or EM10 is true if odd bit inversion is on, and EM00 or EM11 istrue if odd bit inversion is off.

The data actually received is represented as DRe0, DRo0, DRe1, and DRo1(DR=read data). DRe0 is the first actual bit value read from an evenaddress and DRo0 is the first actual bit value read from an odd address.DRe1 is the second actual bit value read from an even address and DRo1is the second actual bit value read from an odd address.

The Set of Logic Gates 2110A is configured to process two bits (DRe0 andDRo0), while the Set of Logic Gates 2110A is configured to process twobits (DRe1 and DRo1). In the illustrated example, Logic Gates 2120 areconfigured to process a total of four bits. In typical embodiments, theSets of Logic Gates 2110A and 2110B are used serially on alternativeclock cycles. Thus, two bits are processed in a first clock cycle andtwo bits are processed in a second clock cycle. Each Set of Logic Gates2110A and 2110B is configured to compress two bits to one bit (DR0 andDR1, respectively) using the enable match values EM00, EM11, EM01, andEM10.

A MUX 2130A is configured to select one of the outputs of the LogicGates 2120 within the Set of Logic Gates 2110A, and a MUX 2130B isconfigured to select one of the output of the Logic Gates 2120 withinthe Set of Logic Gates 2110B. These selections are dependent on which ofthe values of EM00, EM11, EM01, and EM10 are true. This selectionproduces a single bit result, e.g., DR0 or DR1, for each Set of LogicGates 2110A and 2110B.

The second stage of the serial compression Logic 2100 illustrated inFIG. 21 includes a third Set of Logic Gates, generally designated 2110C.These Logic Gates 2140 are responsive to EM00, EM11, EM01, and EM10, aswell as DR0 and DR1. This Set of Logic Gates 2110C is configured tocompare the two results of the first stage of the serial compressionlogic (DR0 and DR1). Because these results are each themselves theresult of a comparison between a pair of bits, the output of the secondstage is dependent on the state of four input bits. The outputs of eachLogic Gate 2140 are received by a MUX 2130C which selects one of theseoutputs, responsive to EM00, EM11, EM01, and EM10, to be the output TDRof the compression logic illustrated in FIG. 21.

The serial compression Logic 2100 illustrated in FIG. 21 results in a4-to-1 compression ratio. The expected data values EM00, EM11, EM01, andEM10 each allow a compression of 2-to-1. Thus, by using these expectedvalues in two logic stages the 2-to-1 compression can be achieved twice,resulting in the 4-to-1 compression ratio of the system. The two stagelogic also allows the compression to be responsive to whether the leastsignificant bit of the address from which data was read is odd or evenand whether odd (or even) bits are inverted. While a 4-to-1 compressionratio could be achieved in a single logic stage, this would typicallyrequire more than four expected data values, and not be responsive towhether the address was odd or even, or not be responsive to whethersome bits were inverted. In alternative embodiments, more than fourexpected data values are used to achieve compression in a single logicstage, and/or a greater compression ratio.

FIGS. 22A and 22B illustrate the application of the compression Logic2100 of FIG. 21. In FIG. 22A, a Table 2210A shows how the inputsTDQ(0-3) 2220 result in a TDQ Output 2260. The value of the output isresponsive to the input values, whether or not the first data bit isfrom an even address (LSB=0 or not) 2230, whether the system isoperating in a default mode 2240A without bit inversion (as opposed to amode where even or odd bits are inverted 2240B), and the values of EM00and EM11. The values shown in Table 2210A are representative of resultsin the default mode 2240A and the values shown in Table 2210B arerepresentative of results in a mode where odd bits are inverted.

FIG. 23 illustrates Logic, generally designated 2300 and used inparallel compression of data received from IC 130. Logic 2300 can beconfigured, for example, to achieve 32-to-8 compression of data. In aFirst Stage 2340 of Logic 2300, a series of Logic 2100 (FIG. 21) areused to compress data as described in relation to FIG. 21. As described,each of Logic 2100 receives and compresses bits in a serial manner. InFirst Stage 2340 this serial compression is performed by several (e.g.,8, 16, 32, 64 or more) Logic 2100 in parallel. The output of each Logic2100 is received by a MUX 2310 configured to perform parallelcompression based on a crossbar multiplexing scheme received from aScheme 2320. Scheme 2320 is a buffer programmed to reflect a desiredcompression scheme.

The desired compression scheme is optionally communicated to Test Module120 from ATE 110 at the same time as test (TDQ) data. In someembodiments, the expected data is communicated through one or moreadditional data pins. For example, in some embodiments, n-Channel Bus115 includes two, three, four or more connections to pins of Test Module120 configured for conveying the compression scheme. In someembodiments, the compression scheme is multiplexed through command pins.In some embodiments, the compression scheme is received from PatternGeneration Logic 214.

MUX 2310 can be a programmable gate array or other circuit known in theart to perform logic operations such as a crossbar multiplexing scheme.MUX 2310 can be hard-coded or programmed using software or firmware. Invarious embodiments, MUX 2310 may be programmed to perform 16-to-8,32-to-8, 64-to-8, 128-to-8, 32-to-16, 64-to-16, 128-to-16, or similarcompression schemes involving greater than 128 bits.

The output of MUX 2310 is received by Output Buffers 2330. OutputBuffers 2330 are configured to receive the compressed data, which mayinclude 8, 16, 32 or more bits. In some embodiments, Output Buffers 2330includes Data Out Register 516.

FIG. 24 illustrates a method of compressing data according to variousembodiments of the invention. In this method, data received from an IC130 is compressed using the logic illustrated in FIGS. 21 and 23. In anoptional Attach ATE Step 2410, Test Module 120 is attached to ATE 110.In an Attach IC Step 2420, IC 130 is attached to Test Module 120. In aReceive Step 2430, test data is received by Test Module 120 from anaddress within IC 130. In a Compress Step 2440, the received data iscompressed to generate compressed data. This compression is optionallyperformed using the logic illustrated in FIGS. 21 and 23. Thiscompression is also optionally responsive to expected data, the addresswith IC 130, and/or a mode in which certain bits are inverted. Thisinversion may involve every other bit (e.g., even bits or odd bits) orpair-wise inversion (e.g., two bits not inverted, two bits inverted, twobits not inverted, etc.). In a Provide Step 2450, the compressed data isprovided to ATE 110.

FIG. 25 is a block diagram of an alternative embodiment of a testmodule, according to various embodiments of the invention. In theseembodiments, Test Module 120 further includes Test Plan Memory 2527configured to store test plans. A test plan may include a sequence oftests. For example, a test plan may be a series of data patterns to besent to IC 130, an over voltage stress test, a synchronization test, arefresh related test (to test, for example, long RAS low failures, andrefresh failure due to insufficient Write recovery time), aworst-case-timing access test (e.g., to screen cell-to-cell leakage,bitline-to-wordline resistive short, bitline-bitline short,wordline-wordline short, or single bit failures), and variouscombinations thereof. A test plan may change depending on the resultsreceived from IC 130 in response to the test signals sent. For example,a test plan may include conditional branches of which tests are tofollow depending on whether the preceding test was successful or failed.

In some embodiments, some portions of a test plan, for example certaindata patterns, may be stored in Test Control 206 while other portions ofthe test plan are stored in Test Plan Memory 2527. In other embodiments,some portions of test plans may additionally or alternatively be inputvia Test DQs 208.

In other embodiments, as described elsewhere herein, testing may involvemultiple Test Mounting Boards 1110 as part of a Test Array 1210. Whentesting multiple modules, test plans stored in Test Plan Memory 2527 maybe shared.

Test Plan Memory 2527, like Test Module Registers 212, may optionally bephysically detachable (e.g., flash memory), from the test module suchthat test plans can easily be modified and/or updated depending on theintegrated circuit or test array to be tested and the various sequencesof tests and conditional branches of testing desired. Test Plan Memory2527 can be predetermined or downloadable, for example from an externalcomputer or other data source, at the start of a test session.

Various embodiments described herein render the test system, as a whole,capable of multiple layers of programming. For example, at one level,standard or more generic tests used for testing multiple classes ofintegrated circuit devices may be programmed and stored in Test ModeRegisters 212. Other, device-specific tests may be programmed prior toeach test session and downloaded into Test Plan Memory 2527. Testsfrequently updated may be suited to being programmed and/or downloadedinto Test Plan Memory 2527 and/or input via TDQ 208. Embodiments inwhich Test Plan Memory 2527 is detachable from Test Module 120 furtherincrease the flexibility of such multiple layers of programming. Inaddition, different levels of programming may apply for command sets,addresses, and test vectors or data patterns. For example, certain testvectors or data patterns are likely to be standard or to recur betweendifferent test sessions (e.g., dependent on the type of IC 130 beingtested). They may be stored in Test Mode Registers 212. Addresses, whichmay be specific to one or a few test sessions may be programmed and/ordownloaded into Test Plan Memory 2527. Commands, which may optionallyvary depending on the results of prior tests in a test sequence, may beinput via TDQ 208.

In some embodiments, Test Module 120 further includes a Clock AdjustmentCircuit 2528, as illustrated in FIG. 25. Clock Adjustment Circuit 2528is configured to test aspects of an integrated circuit related to clocksynchronization, for example set-up time and hold time. To test suchaspects of the integrated circuit, Clock Adjustment Circuit 2528 isconfigured to adjust the edges of the reference clock signal relative tothe edges of test signals. Test signals comprise commands, addresses,and/or data patterns. Clock Adjustment Circuit 2528 is configured toadjust the edges by adjusting the synchronization between the clockreference signal output from Clock Driver 2520 and one or more of thetest signals sent from Command Driver 2522, Address Driver 2524, and/orData Interface 2526 to IC 130. An adjustment may be made in response toone or more signals received from ATE 110 or a test plan.

Various aspects of the integrated circuit may be tested by adjustingdifferent parameters. Different manners of adjustment may be useddepending on the parameter of interest. For example, tRC, tRCD, tRP,tAC, tS, and tH may be adjusted by delaying the signal or signals ofinterest (e.g., by using delay elements such as a larger number offlip-flops). Some parameters, such as tRC, tRCD, tRP, may additionallyor alternatively be tested by adjusting the clock reference signaloutput from Clock Driver 2520.

In some embodiments, an adjustment is made by Clock Adjustment Circuit2528 to the signal going to Clock Driver 2520. As a result, anadjustment will apply to the output from Clock Driver 2520 and the testsignals conveyed to IC 130 from Command Driver 2522, Address Driver2524, and Data Interface 2526. In these embodiments, Test Module 120 iscapable of testing the sensitivity of IC 130 to each clock adjustment.

In yet other embodiments, an adjustment is made to the clock signalcontrolling the output of individual data channels of the test signalsconveyed to IC 130. Individual adjustments are made by Clock AdjustmentCircuit 2528 to the signals going to, for example, one or more commandsof Command Driver 2522, one or more address lines of Address Driver2524, or one or more bits of Data Interface 2526. The adjusted generatedtest signals, including the adjusted data channels as well as the otherunadjusted data channels, are conveyed to IC 130 via Command Driver2522, Data Address Driver 2524, or Data Interface 2526, respectively.Data from IC 130 received in response to the adjusted generated testsignals are read by Data Interface 2526 and, optionally, a comparison ismade to expected test results. In these embodiments, Test Module 120 iscapable of testing the sensitivity of individual bits or lines, or acombination or set thereof, of IC 130 to a variety of time critical andslew rate sensitive parameters, such as set-up and hold time.

FIG. 26 illustrates a slew rate of a test signal. Slew rate is the rateof change of a signal rising from low to high or falling from high tolow. It is measured, on the rising edge, between 10% 2610 of the fullsignal amplitude 2630 and 90% 2620 of the full signal amplitude and, onthe falling edge, between 90% 2640 of the full signal amplitude and 10%2650 of the full signal amplitude. The maximum slew rate sets an upperboundary on the frequency at which signal transitions may be tested and,in turn, limits the maximum data rate. Reliable testing of parameterssensitive to clock synchronization, such as set-up time and hold time,requires a slew rate sufficiently fast to test the parameter at issue.

The length of the path traveled by a signal affects its slew rate. Forexample, the length of the cables between existing external testingequipment and the integrated circuits under test is sometimes on theorder of meters. This may result in the input signals to the integratedcircuit having slew rates too slow to reliably test some parameters.Test Module 120 is configured to be placed in close proximity to or onthe same silicon die as IC 130. Therefore, in some embodiments, thelength of the signal paths between Test Module 120 and IC 130 can bemade insignificant with respect to its effect on slew rate. This allowsTest Module 120 to more precisely shape signals conveyed to and receivedby IC 130. For example, in some embodiments, the slew rate of atransition from low to high between Test Module 120 and IC 130 is lessthan one nanosecond.

In some configurations, the faster slew rate (relative to the prior art)at which signals are conveyed from the output components of Test Module120 to IC 130 may be used to test time sensitive parameters such asminimum set-up time and minimum hold time. The set-up time is the amountof time data signals must be stable prior to the active clock edge. Thehold time is the amount of time data signals must be maintained past theactive clock edge for the data to be stable upon sampling. To test theseand other parameters, the test equipment is optionally configured foradjusting the relative timing between the clock reference signal and thegenerated test signals conveyed to IC 130.

FIGS. 27A-D illustrate the relationship between the clock referencesignal conveyed from Clock Driver 2520 (including any adjustment made byClock Adjustment Circuit 2528) to IC 130, the generated test signals,and the clock reference controlling the generated test signals. Theclock reference controlling the generated test signals comprises thesignals from Clock Adjustment Circuit 2528 to Command Driver 2522,Address Driver 2524, and/or Data Interface 2526, respectively. In someembodiments, IC 130 is clocked on the rising clock edge, for example ina single data rate memory device. Data is sampled when a command (CMD)is received at clock edge 2720. In embodiments clocked on the risingedge, the set-up time 2755 is the period following active clock edge2710 from the time 2735 when the data signal reaches 90% of its fullamplitude and thus becomes stable until the time 2745 when data issampled. The hold time 2760 is the period from the time 2745 when datais sampled until the time 2750 when the amplitude of the data signalfalls to 90% of its full amplitude and thus becomes unstable.

FIG. 27A illustrates the clock reference signal conveyed from ClockDriver 2520 to IC 130 (i.e., the original unadjusted clock referencesignal). FIG. 27B illustrates the generated test signals. The originalunadjusted clock reference signal is responsible for sampling thegenerated test signals. A short delay may occur between clock edge 2705and the time 2725 when the generated test signals respond to clock edge2705 and changes (e.g., from high to low or from low to high).

By adjusting the relative relationship between the original unadjustedclock reference signal and the clock reference signal controlling thegenerated data (illustrated in FIG. 27C), the minimum set-up time andhold time may be tested. The clock adjustment 2770 is the differencebetween the active clock edge 2710 of the clock reference signalconveyed to IC 130 from Clock Driver 2520 and the active edge 2765 ofthe clock reference signal controlling one or more data channels toCommand Driver 2522, Address Driver 2524, and/or Data Interface 2526.

FIG. 27D illustrates the one or more data channels of the generated dataadjusted by the clock reference signal in FIG. 27C. As illustrated inFIG. 27D, the set-up time 2775 of the one or more adjusted data channelsdecreases compared to the set-up time 2755 of the generated data priorto the adjustment. Likewise, the hold time 2780 increases compared tohold time 2760. By varying the adjustment 2770, the sensitivity of IC130 to set-up time as well as hold time may be tested. It should benoted that while the timing of the generated test signals is dependenton the adjusted clock reference signal (and thus adjusted in FIG. 27Drelative to FIG. 27B), the sampling of the generated test signals isstill responsive to the original unadjusted clock reference signal.

In some embodiments, IC 130 is clocked on a falling clock edge. When theactive clock edge 2715 is falling, the set-up time becomes morecritical, because the time for the signal to become stable is decreased.This decrease is illustrated in FIGS. 27B and 27D. In FIG. 27B, on afalling clock edge 2715, the set-up time is the time between time 2745and time 2750, which is shorter than the set-up time 2755 that resultswhen IC 130 is clocked on the rising clock edge 2710. In FIG. 27D, on afalling clock edge 2785, the set-up time is the time between time 2790and time 2795 (when the data is sampled), which again is shorter thanthe set-up time 2755 that resulted when IC 130 is clocked on the risingedge 2710.

In some embodiments, Clock Adjustment Circuit 2528 may comprise a delaylocked loop, which allows for generating both positive and negativeadjustments. For example, instead of applying a positive 105%adjustment, a negative 95% adjustment may be made. Whereas a positiveadjustment 2770 results in a relative decrease in the set-up time andincrease in the hold time, by analogy, a negative adjustment 2770 wouldresult in a relative increase in the set-up time and a relative decreasein the hold time.

In some embodiments, Clock Adjustment Circuit 2528 is capable ofgenerating incremental adjustments through the full range of a clockcycle (e.g., 5% of the clock cycle, 10% of the clock cycle, etc.) and/orthe next clock cycle (i.e., in excess of a full clock cycle). An exampleof an adjustment in excess of a full clock cycle 2798 is illustrated inFIGS. 27A and 27C between rising clock edge 2705 and the correspondingrising clock edge at 2765.

One full clock cycle corresponds to the width of a data eye 2730. Thedata eye 2730 is the center of an eye diagram depicting digital datatransitions from low to high over a period of three clock cycles.

FIG. 28 illustrates methods for determining whether IC 130 passes aset-up or hold time test, according to various embodiments of theinvention. In a Center Eye Step 2810, the eye 2730 of the generated datais first centered around a data sampling time using one of severaltechniques existing in the prior art. In a Generate Adjustment Step2820, an adjustment is generated via Clock Adjustment Circuit 2528. Theadjustment is applied to Clock Driver 2520 or to the individual outputsof Command Driver 2522, Address Driver 2524, and/or Data Interface 2526.In a Convey To IC Step 2830, the adjusted generated data is conveyed toIC 130 via Data Address Driver 2524, Command Driver 2522, and/or DataInterface 2526. In a Receive Step 2840, data from IC 130 received inresponse to the adjusted generated test signals are read by DataInterface 2526. In a Compare Step 2850, a comparison is optionally madeto expected test results (e.g., by comparison to specified values orspecifications). Optionally, the test sequence may be repeated fromGenerate Adjustment Step 2820 by making additional adjustments. In thismanner, Test Module 120 is capable of determining whether IC 130 passedor failed one or more set-up time or hold time tests.

Test Module 120 when configured to operate with Clock Adjustment Circuit2528 in one of the described configurations and embodiments is furthercapable of operating at two different clock frequencies, as describedelsewhere herein.

FIG. 29 illustrates a circuit diagram for testing set-up or hold time.As described elsewhere herein, a clock adjustment in excess of one clockcycle may be used in some test scenarios for testing time and slew ratesensitive parameters. An adjustment in excess of one clock cycle, forexample 1.2 clock cycles, comprises an integer number of full clockcycles (e.g. 1) plus a fraction of a clock cycle (e.g., 0.2). Flip Flop2910 is configured to delay a data channel signal 2905 by an integernumber of clock cycles. In some embodiments, Flip Flop 2910 may comprisemultiple flip flops. Flip Flop 2925 is configured to select either theunadjusted data channel signal 2905 or the adjusted data channel signal2915 for clocking to an Adjustment Component 2935. Flip Flop 2925 isconfigured to make the selection in response to a select input signal2920 received from ATE 110, a test plan or test pattern (e.g., stored inTest Mode Registers 212 and/or Test Plan Memory 2527), and/or Test DQs208. Adjustment Component 2935 is configured to further adjust datachannel signal 2930 by a fraction of a clock signal (e.g., 0.2 clockcycles) in response to an adjustment signal 2940 conveyed from ClockAdjustment Circuit 2528 to Command Driver 2522, Address Driver 2524, orData Interface 2526. For example, if the data channel signal is addressline A0, adjustment signal 2940 is the individual adjustment to thatparticular address line conveyed from Clock Adjustment Circuit 2528 toAddress Driver 2524. In this manner, the data channel signal 2945 outputfrom Adjustment Component 2935 has been adjusted for the integer as wellas the fraction of a clock cycle. Buffer 2950 is configured to store theadjusted data channel signal 2945 prior to conveying adjusted datachannel signal 2955 (e.g., address A0) to IC 130. In alternativeembodiments, Flip Flop 2910 may be omitted and Adjustment Component 2935may perform the full adjustment desired, including adjustments by a fullclock cycle or more, in response to the adjustment signal 2940 received.Adjustments of a fraction of a clock cycle may be accomplished using ananalog and/or digital delay line. In various embodiments, adjustments assmall as 0.05, 0.1, 0.2 and/or 0.5 clock cycles are possible.

FIG. 30 illustrates alternative methods of testing IC 130 using TestModule 120, including an Adjust Step 3010, according to variousembodiments of the invention. Attach ATE Step 1310, Attach IC Step 1320,Configure Test Module Step 1330, Receive Test Signals Step 1340,Generate Step 1350, Send Test Signals Step 1360, Receive Results Step1370, Report Step 1380, and Detach IC Step 1390 are performed asdescribed elsewhere herein.

In addition, Configure Test Module Step 1330 may include specifying testplans stored in Test Plan Memory 2527 and/or in Test Mode Registers 212,and/or test signals input from ATE 110 to Test DQs 208. In Receive TestSignals Step 1340, the signals received by Test Module 120 may,optionally, be received at a first slew rate. Generate Step 1350typically includes the use of Test Plan Memory 2527 and/or the use ofAddress Generator 210 to generate test addresses, and/or the use of TestPlan Memory 2527 and/or Pattern Generation Logic 214 and Write DataLogic 216 to generate test signals.

In an optional Adjust Step 3010, timing of one or more data channels ofthe test signals generated in Generate Step 1350 is adjusted relative tothe clock reference signal. Adjust Step 3010 includes the use of ClockAdjustment Circuit 2528 to generate the adjustment. The generation anduse of adjustments are described elsewhere herein. The adjustment ofAdjust Step 3010 may be configured to test set-up and/or hold times.

In a Send Test Signals Step 1360, the test signals sent from Test Module120 to IC 130 are additionally adjusted in Adjust Step 3010.Furthermore, the test signals generated in Generate Step 1310 areoptionally sent at a second, faster, slew rate.

In a Report Step 1380, in some embodiments, the expected result may bestored in Test Plan Memory 2527. In some embodiments, the valueindicating “Pass” or “Fail” may be output in response to multiplecomparisons, e.g., as an indication of whether a set of tests includedin a test plan, as a whole, passed or failed.

Several embodiments are specifically illustrated and/or describedherein. However, it will be appreciated that modifications andvariations are covered by the above teachings and within the scope ofthe appended claims without departing from the spirit and intended scopethereof. For example, in some embodiments, all or part of Test Module120 is incorporated within ATE 110 as a detachable module. In theseembodiments, Test Module 120 is optionally replaceable in order toupgrade ATE 110. Test Module 120 is optionally included in a read headof ATE 110. In some embodiments, Testing Interface 120 is optionallyconfigured to perform repairs to IC 130. For example, Testing Interface120 may include circuits configured to burn fuses within IC 130 orconfigured to convey repair signals from ATE 110 to IC 130. While theinversion of odd bits is discussed herein, one of ordinary skill in theart would understand that the inversion of even bits may be accomplishedin an equivalent approach.

In some embodiments of the invention, Test Module 120 is configured forselecting which component to test, from among several components withinan electronic device. For example, Test Module 120 may be included in aSiP and be configured to select one of a plurality of different memorieswithin the SiP for testing. In these embodiments, a first instance ofTest Module 120 may be included in the SiP and a second instance of TestModule 120 may be disposed between ATE 110 and the SiP. The firstinstance of Test Module 120 is used for selecting which circuits to betested in a test mode and the second instance of Test Module 120 is usedto test the SiP at a higher clock frequency than that of ATE 110.

The embodiments discussed herein are illustrative of the presentinvention. As these embodiments of the present invention are describedwith reference to illustrations, various modifications or adaptations ofthe methods and or specific structures described may become apparent tothose skilled in the art. All such modifications, adaptations, orvariations that rely upon the teachings of the present invention, andthrough which these teachings have advanced the art, are considered tobe within the spirit and scope of the present invention. Hence, thesedescriptions and drawings should not be considered in a limiting sense,as it is understood that the present invention is in no way limited toonly the embodiments illustrated.

What is claimed is:
 1. A system comprising: a data compression componentto compress data received from an integrated circuit under test at afirst clock frequency, to generate compressed data; and a data outputcomponent, operatively coupled to the data compression component, toconvey the compressed data to automated testing equipment at a secondclock frequency.
 2. The system of claim 1, wherein the second clockfrequency is different than the first clock frequency.
 3. The system ofclaim 2, wherein the second clock frequency is a lower frequency thanthe first clock frequency.
 4. The system of claim 1, wherein the datacompression component is to compare the received data to an expecteddata result and to communicate an output to the automated testingequipment.
 5. The system of claim 4, wherein the data output componentis included in a test module, the test module being one of a pluralityof test modules included in a test array to test a plurality ofintegrated circuits.
 6. The system of claim 5, wherein the test arraycomprises a memory to store the expected data result, and wherein thememory being shared by the plurality of test modules.
 7. The system ofclaim 1, wherein the data compression component is to compress the datareceived from the integrated circuit responsive to whether an address ofthe data is even or odd.
 8. The system of claim 1, wherein the datacompression component is to compress the data received from theintegrated circuit responsive to an invert odd or even bit mode.
 9. Thesystem of claim 1, wherein the data compression component is configuredto compress the data received from the integrated circuit in a serialcompression stage.
 10. The system of claim 9, wherein the serialcompression stage comprises multiple comparisons of the data receivedfrom the integrated circuit to an expected data value.
 11. The system ofclaim 1, wherein the data compression component is to compress the datareceived from the integrated circuit in a parallel compression stage.12. The system of claim 1, wherein the data compression component is tocompress the data received from the integrated circuit in both a serialcompression stage and a parallel compression stage.
 13. The system ofclaim 1, wherein the data compression component is to compress the datareceived from the integrated circuit by a ratio of 4-to-1 or greater.14. The system of claim 1, further comprising the automatic testingequipment, wherein the automatic testing equipment is coupled to thedata output component to test the integrated circuit.
 15. A systemcomprising: a data compression component to compress data received froman integrated circuit to generate compressed data, the compression beingresponsive to an address within the integrated circuit from which thedata was received; and a data output component, operatively coupled withthe data compression component, to convey the compressed data toautomated testing equipment.
 16. The system of claim 15, wherein thecompression is further responsive to a mode in which odd bits or evenbits are inverted.
 17. The system of claim 15, further comprising two ormore pins configured to receive an expected data result, and wherein thedata compression component is to compare the received data to theexpected data result and to communicate an output to the automatedtesting equipment.
 18. The system of claim 15, wherein the compressionis further responsive to expected data received from the automatedtesting equipment.
 19. A method comprising: compressing received dataresponsive to expected data, to generate compressed data; and providingthe compressed data to automated testing equipment.
 20. The method ofclaim 19, wherein the received data is received from an integratedcircuit at a first clock frequency and provided to automated testingequipment at a second clock frequency, and wherein compressing thereceived data is responsive to an address within the integrated circuitfrom which the received data was received.